Life History and Ecology of the Five-lined Skink, Eumeces fasciatus Part 3

HABITAT IN NORTHEASTERN KANSAS

In northeastern Kansas I have collected or observed this skink in several dozen localities, and searched unsuccessfully in numerous other localities. Absence of this skink, in some situations and its presence and relative abundance in others, provided a basis for appraising the environmental factors that are of critical importance. River valleys, of the Kaw and Wakarusa and their tributaries, with deep alluvial soil, alternate with flat or rolling upland some two hundred feet higher in elevation, and having shallow, rocky soil. Where the uplands slope to the valley floors, there are steep hillsides, usually with extensive limestone outcrops along their upper slopes. The alluvial plains formerly supported hardwood forests, while the hill slopes and uplands were largely prairie. At the present time the bottomland forest has been almost completely destroyed, as it grew on the most fertile and potentially productive soil, and has been replaced by cultivated crops.

There are still trees along streambanks, and in occasional woodlots, but I have failed to find any skinks in such situations. I doubt that they ever have been numerous in the bottomland woods; lack of rocks for shelter, and periodic flooding are unfavorable factors. In the Kaw flood of June and July, 1951, for instance, the entire valley was inundated, and in smaller tributary valleys such as that of the Wakarusa, flooding is frequent at the season when skinks are incubating their eggs. The uplands, formerly prairie, now are used partly for cultivated crops and partly for pasture. The soil is poor and rocky, and now heavily eroded.

The pastures mostly have a weedy type of vegetation indicative of overgrazing. Five-lined skinks are absent from most of this upland.

The steep slopes from the upland to the valley floor are now mostly wooded, and the population of skinks is chiefly in this band of woodland. Some of the hillsides that have relatively gentle slopes are treeless and are used for pasture, or are even under cultivation. Where second growth forest is present its aspect differs depending upon slope, exposure, and past treatment. Osage orange and honey locust are aggressive invaders on some dry hillside pastures, and in this type of woods the skinks are scarce or absent. Some hillside areas, especially on moist north slopes have thick second-growth woods, in which elm is usually the princ.i.p.al tree, with several oaks and hickories, walnut, hackberry, coffee tree, locust and osage orange, and with a dense understory vegetation of dogwood, gooseberry and coralberry, with vine tangles of grape, poison oak, and greenbrier. Such woodlands provide little food for livestock, and are often fenced off from adjacent pastures. The shading creates conditions unfavorable for skinks and they are relatively scarce in the denser woods. They are much more numerous in woodlands that are fenced in with pastures heavily grazed by cattle or horses, with understory vegetation kept cropped back, and with more open ground and patches of sunlight. However, they are absent or scarce in woods that have been subjected over periods of years to browsing, by sheep or goats, so heavily that hardly any herbaceous vegetation remains and so heavily that the soil is packed from trampling. Along the upper slopes, especially about heads of gullies, in areas strewn with flat rocks, in fairly open mixed woods, with some decaying wood on the ground, habitat conditions are most nearly optimum for the skinks.

Artificial habitat features, such as rock piles, stone walls, wood piles, rail fences, or old deserted buildings and sheds, with loose boards lying about on the ground may support unusually high concentrations of skinks when the surrounding habitat is favorable.

STUDY AREAS

The University of Kansas Natural History Reservation where most of the field work for this study was done, has been described in a recent publication (Fitch 1952:8). While records were obtained from scattered points throughout the 590-acre Reservation and elsewhere in northeastern Kansas, field study of this skink was concentrated on four relatively small areas totalling only about ten acres in extent (Figure 26). These areas were selected on the basis of abundance and availability of the skinks, and of variety of habitat conditions represented.

One of these sites was a deserted quarry on a southward projecting spur of the plateau-like cuesta top, where the upper layers of the Oread limestone are prominently exposed. In the course of operations, begun about 1937, the area was denuded of trees and shrubs, and the upper layers of limestone were removed from a strip about 50 feet wide and more than 100 yards long. The exposed outcrop presented a vertical rock face five to ten feet high, with south and southeast exposure. Numerous jagged seams and fissures in the rock hastened its disintegration.

Quarrying had been discontinued several years before the present study was begun in 1948. At that time there were talus-like acc.u.mulations of rock and soil several feet wide along the base of the rock face, supporting a luxuriant pioneer vegetation especially, sweet clover, stickleaf, ragweed and elm seedlings.

The habitat conditions provided by the exposed rock outcrop at the border of woods and open land, proved unusually favorable for reptiles in general, and it was one of the most productive sites on the Reservation for Sonoran skinks, collared lizards, racerunners, ring-necked snakes, blue-racers, bull snakes, pilot blacksnakes, scarlet king snakes, slender tantillas, copperheads, and timber rattlesnakes.

For the five-lined skink, however, this disturbed area was marginal, and supported only a spa.r.s.e population. Several decaying two-inch boards were preferred hiding places where the skinks were found most frequently, and remains of collapsed rock walls, one in the center of the area and one at the edge of the woods, were also occupied. Skinks may have tended to wander away to more favorable situations or may have been more subject to predation than those elsewhere, since the incidence of recaptures was relatively low. Most of the records from this general area were from a ledge in adjacent woods rather than from the quarry itself. Another site was a rock fill in a ravine below a pond made in 1937. This rock fill was 70 feet long, up to 30 feet wide, and three feet deep. East and north of the rock pile was a gra.s.sy dike, and beyond it the pond. On the west open gra.s.sland extended approximately 200 feet to the edge of the woods, with a diversion ditch at its border. On the south end, the rock pile was adjacent to woodland at the base of a steep slope with north exposure. On this slope the dense stand of second growth oak and hickory with an almost continuous leaf canopy was a poor habitat. The rock pile was thus partly isolated and surrounded by areas that were either uninhabitable to the skinks or supported only spa.r.s.e populations of them. By 1948 the rock pile was partly covered by grape vines. Dead leaves and other debris had acc.u.mulated in the deeper interstices between the rocks. Spiders, beetles, snails and other small animals were extremely numerous in the vicinity of the rock pile and provided an abundant food supply. A large sycamore on the west side of the rocks provided some afternoon shade. This rock pile provided shelter for reptiles other than the five-lined skink--especially the garter snake, water snake, copperhead, and brown skink. Another area of about two and a fourth acres ("Skink Woods," Figure 21) was the one most productive of skinks. It is a wooded upper slope adjacent to a hilltop pasture. Along the hilltop rim the upper stratum of the Oread limestone presents a rock face as much as four feet high at the north end, but less exposed at the south end where it was partly covered by deposited soil. Approximately 100 feet down the slope a second outcropping is present, with many loose rocks and boulders throughout the whole area.

Soil is light and loamy. The slope has a west exposure. The stand of trees is fairly open, with several large elms, walnuts, and yellow oaks, and occasional hackberries, ailanthus and red haws. This area was included in a narrow strip of woodland fenced about 1940 as a runway connecting a hilltop pasture with a valley pasture where water was available at a time when both pastures were heavily grazed by horses and cattle. As a result of trampling, browsing and grazing by livestock, understory vegetation of this area presented a different aspect from that in most other parts of the woodland. Saplings of the dominant tree species and shrubs, notably dogwood, gooseberry and crabapple, were relatively scarce. Herbaceous vegetation, especially muhly gra.s.s, was conspicuous. By 1953 in the fifth growing season after livestock were removed, the area still contrasted with other parts of the woodland in spa.r.s.eness of shrubby vegetation. Old stock trails were still discernible, and some sheet erosion and gullying had occurred. The effect of livestock in holding back woody undergrowth seemed to be an important factor in improving the habitat as the skinks were much scarcer in adjacent woodlands on either side that were similar in species composition, size, and numbers of the larger trees, but different in having much thicker underbrush. These adjacent woodlands were not entirely comparable, however, because they had more north-facing exposures. Reptile a.s.sociates in the Skink Woods area include the brown skink, Sonoran skink, gla.s.s-snake, worm snake, ring-necked snake, blue-racer, garter snake, pilot blacksnake, copperhead and timber rattlesnake, but only the worm snake and ring-necked snake were abundant.

Rat Woods, an area of approximately four acres, was like Skink Woods, formerly the upper part of a connecting strip between hilltop and valley pastures and was altered by the effect of concentrated trampling and browsing by livestock. It is V-shaped, with the apex at the north end, and the slope exposures southwest and southeast. The area is bisected from north to south by a small gully, and remains of an old rock wall.

To the east of this gully the lower outcrop is prominent but west of the gully, it is but little developed. As compared with other wooded areas, this one was relatively dry. Trees, and other vegetation in general, are somewhat more xeric in aspect than are those in Skink Woods. Along the upper ledge are elms and hackberries, with many thick clumps of fragrant sumac. The trees are mainly elm, walnut, honey locust, and osage orange with hardly any oaks or hickories and, with shrubby undergrowth of dogwood, gooseberry, and coralberry spa.r.s.er than in adjacent woodlands.

Herbaceous vegetation consists largely of muhly gra.s.s, geum, and avens.

On the hilltop edge above the ledge are many flat rocks of varying sizes, and the slope is thickly strewn with rocks, some of the larger ones deeply embedded in the soil. The population of five-lined skinks was relatively spa.r.s.er than in Skink Woods. Other reptiles including the Sonoran skink, racerunner, gla.s.s-snake, worm snake, ring-necked snake, blue-racer, bull snake, pilot blacksnake, garter snake, scarlet king snake, slender tantilla, and copperhead, were more numerous in this area than in most other parts of the Reservation. The comparatively scarce prairie skink was found only in this area, and the scarlet king snake and slender tantilla were found only here and at the quarry.

The Annual Cycle of Reproduction and Growth

SEASONAL OCCURRENCE

Collectors and other observers have often noted that reptiles, in general, are not found in equal abundance throughout the entire season of their activity. Many kinds are most in evidence within a period of weeks after emergence from hibernation, which corresponds with the time of breeding and later they become much scarcer. In skinks of the genus _Eumeces_ this tendency is perhaps even more p.r.o.nounced than in most other kinds of reptiles. By midsummer or considerably earlier their period of greatest activity is pa.s.sed, and in some kinds, adults, or individuals of any size can rarely be found in the latter half of the growing season, even by a skilled collector familiar with their habitats and habits. Thus, Taylor (1936:5) in the preface of his revision of _Eumeces_, describing the difficulties involved in a.s.sembling needed series of the many Mexican species by collecting on summer field trips, wrote: "In 1934 in western Mexico ... I met with most disheartening results ... (although more than 1500 specimens were collected) only a single specimen of _Eumeces_ was taken. Hobart Smith, in 1934, accompanied by David Dunkle, made a journey into northwestern Mexico ...

and while generally successful, likewise obtained only a single specimen of _Eumeces_."

[Ill.u.s.tration: FIG. 7. Seasonal occurrence of five-lined skinks, based on data collected in 1949, 1950, 1951, and 1952; adult males and adult females are taken in greatest numbers in May, and in progressively smaller numbers through the summer and autumn; yearlings are found in increasing numbers through March, April, May, and June, then in decreasing numbers through the summer and autumn.]

In the present study the tendency of _E. fasciatus_ to concentrate its surface activity in early spring was clearly shown. In unseasonably warm weather in early spring, even in February in one instance, individual skinks have been found active on the surface or beneath flat rocks warmed by the sun; but general emergence ordinarily does not occur until sometime in April, depending on the weather. Unless the weather is much warmer than the seasonal norm, the skinks spend much of April in a torpid condition, either not becoming fully active until late in the month, or lapsing into torpidity with the return of cool weather after their first emergence from hibernation. During warm periods in April, however, activity is at or near its annual maximum for all individuals regardless of s.e.x or age.

In May, with the advent of much warmer weather, daytime temperatures are usually high enough for the skinks to be active. Adult males travel about more actively and persistently than females or young, and as a result they are found so much more frequently that the numbers taken approximate those for adult females and young combined. Many of the adult males recorded in May were taken in funnel traps or pitfalls.

Active males in the open were difficult to catch, and a high percentage of them escaped. To the casual collector or observer, these skinks are much more in evidence in May than at any other time of year, and most of those seen are adult males. By June, the numbers of skinks seen in the open decline abruptly. The adult males become relatively scarce, with reduction from more than half to about one-sixth of the total, and the young, about half-grown at that season, make up approximately half of the total. The adult females make up approximately one-third of the total June sample, but few of them were found active on the ground surface. Most were found in nest burrows beneath flat rocks. Under such conditions they tended to be sluggish in behavior, and were caught much more easily than were males and young. July was characterized by progressive decrease in the numbers of adult males, adult females, and second year young, whereby the numbers of each group were little more than half of those for June; and by appearance of a new crop of hatchlings which made up about one-third of the month's sample.

Hatchlings first appeared from early July to late July in different years; few were recorded in July in some years. Females were much less commonly found in nests in July than in June because many nesting attempts were terminated before the beginning of July or early in the month, and probably because those that remained were often more deeply buried and better concealed. By August the adult males, and the second year young (by then approaching adult size) were found in still smaller numbers, but the number of hatchlings and of adult females approximated those recorded in July. In the females there is evidently some resumption of activity after the incubation period is terminated. The females are then hungry and sometimes emaciated, weighing less, on the average, than the year-old young of shorter snout-vent length. The numbers of hatchlings are augmented through early August in some years, as late broods continue to hatch. By early September few skinks except hatchlings are to be found, and activity continues to wane throughout the month. In October skinks of any age or s.e.x group are a rarity, even though temperature is about the optimum for their activity. Little is known concerning where and how they spend the fall months. Probably they are not actually dormant, but retreat underground where temperature is moderate and humidity is high. Individuals kept in captivity at this season were listless showing but little inclination to feed. The only five-lined skink taken on the Reservation in November was found in a funnel trap after a rain at the end of a long drought. It may have been attracted to the surface by moisture.

The following table shows the dates on which various events of the annual cycle were observed in each of five different years. Owing, to the secretive habits of the skinks, these events generally were not observed until somewhat after their earliest occurrence in any one season. The lag was greater in some instances than in others.

Table 3. Phenology of the Annual Cycle in Five Different Years.

=====================+=========+=========+=========+=========+========= _1949_ _1950_ _1951_ _1952_ _1953_ ---------------------+---------+---------+---------+---------+--------- Earliest emergence from hibernation Mar. 30 ....... Mar. 24 Mar. 29 Mar. 20 General emergence from hibernation ....... Apr. 7 Apr. 14 Apr. 17 Mar. 27 Breeding coloration appearing in males ....... Apr. 15 Apr. 25 Apr. 28 Apr. 16 Peak of breeding season May 3 May 12 May 16 May 10 May 7 Females starting nest burrows May 26 May 24 May 19 May 19 May 24 Last appearance of gravid females June 10 June 17 June 29 June 9 .......

Earliest appearance of eggs June 10 June 13 June 24 June 22 June 16 Earliest appearance of hatchlings July 5 July 15 July 23 July 3 July 13 Latest hatching date July 15 Aug. 8 Aug. 8 July 14 .......

Latest fall record Oct. 15 Sept. 19 Sept. 26 Nov. 9 Oct. 12 ---------------------+---------+---------+---------+---------+---------

s.e.xUAL CYCLES AND BEHAVIOR

Reynolds (1943:370 and 1947:191) studied the histological and gross seasonal changes in the reproductive organs of the adult male _Eumeces fasciatus_. There is a well defined annual cycle. "Early seasonal increase in seminiferous epithelial heights and in diameter of lumina and tubules reached a maximum in April followed by regression reaching complete involution by August. Late seasonal revival of activity results, by November, in size of testicular elements comparable to those seen in January. Primary spermatocytes predominate in the germinal epithelium in January, secondary spermatocytes and spermatids in February, with spermatids and metamorphosing sperm dominating from March until late June when the germinal material of the current season is exhausted." Fifty-three adult males were used as a basis for his study.

These were of diverse origins from Arkansas, Florida, Missouri, Tennessee, and Indiana. Since s.e.xual cycles in such widely ranging species tend to be synchronized with local phenology, and change somewhat from one region to another, the seasonal cycle may have been somewhat obscured by the diverse origins of the material. The Florida specimens may have been of the species _E. inexpectatus_. Apparently Reynolds' experimental skinks were kept in captivity for varying lengths of time before their reproductive organs were examined. The normal cycle would almost certainly be altered in captivity, especially in skinks kept at high temperatures during the time that they would normally be hibernating.

The seasonal change in gross appearance of the testes is not great. In the breeding season the testes are slightly enlarged and are firm and engorged, with pinkish or orange tinge. In immature males, and adults that are not in breeding condition, the testes are smaller, attenuate, paler colored, and flaccid. Sizes of testes in some males killed in the breeding season are recorded in Table 4.

Table 4. Sizes of Testes in Spring and Early Summer in s.e.xually Mature and Juvenal Males.

==============+===============+===============+=============== Snout-vent Sizes of Age Date length in mm. testes in mm. cla.s.s --------------+---------------+---------------+--------------- May 6, 1951 76 7.0 4.0 old adult May 20, 1951 77 5.0 2.8 old adult May 20, 1951 74 6.2 3.2 old adult May 20, 1951 74 5.5 3.0 old adult May 20, 1951 66 5.0 2.8 young adult May 20, 1951 65 4.2 3.2 young adult May 20, 1951 64 5.3 3.1 young adult May 20, 1951 45 2.5 1.0 juvenile May 20, 1951 40 1.5 .3 juvenile June 3, 1951 65 5.0 2.5 young adult June 10, 1951 67 4.0 1.8 young adult June 25, 1951 75 4.0 2.0 old adult June 25, 1951 70 3.5 1.8 young adult June 25, 1951 51 2.0 .5 juvenile --------------+---------------+---------------+---------------

From the time of emergence in spring, males show some tendency to seek out females, and frequently a pair may be found together under the same rock, weeks before the onset of the breeding season. There is no satisfactory evidence that such a.s.sociations have any permanence. At the time of emergence from hibernation the males rarely have even a trace of reddish coloration on their heads, and more than a month normally elapses before attainment of breeding coloration. Each year that observations were made activity of the skinks was interrupted by cold weather in April, so that the lizards were fully active for only part of the time between their earliest emergence and their attainment of breeding condition five to eight weeks later. The reddish suffusion of the breeding season, hardly showing in the first few weeks after emergence, appears suddenly within a few days in all adult males of the population. The best indication of the time necessary to attain breeding condition was provided by an adult male whose hibernation was interrupted on December 15 by bringing him into a warm room where he was kept at 80 F. or more in the daytime, and approximately 70 F. at night. Thirteen days later, on December 28, the male had developed a noticeable reddish suffusion. On January 3, nineteen days after hibernation terminated, the suffusion was near its maximum. When an adult female was placed with the male on this date, he showed s.e.xual interest but the courts.h.i.+p was not consummated. On January 6, the 22nd day, the male's colors had reached their maximum, and when the female was placed with him, pursuit and copulation occurred promptly.

In the spring of 1952, the first skink of the season was found on March 29, still only partly activated, and under a large flat rock. Skinks were not caught or seen in any numbers until April 17, however, and general emergence probably occurred only a day or two earlier than this.

On May 10, 1952, breeding activity was estimated to be at its peak. By May 28, the reddish suffusion was conspicuously faded in several males taken. By June 10 it was no longer discernible.

In the immature female the oviducts are small and threadlike, and the ovaries have grapelike cl.u.s.ters of pale whitish eggs, which are minute, often less than .5 mm. in diameter (Figure 8A). In s.e.xually mature females ova enlarge rapidly after emergence from hibernation in the spring. While eggs are still in the ovary, they are approximately spherical. In late April and early May the developing ova enlarge rapidly. Approximate average sizes (dimensions in mm.) of developing ovarian ova in each of 22 mature females on different dates were as follows: April 17, 1949: 2.6, 2.3, 2.2, 2.2, 1.9, 1.9; April 18, 1949: 2.2, 1.9, 1.8, 1.1, 1.1; April 24, 1949: 4.6, 3.2, 2.5, 2.3; May 6, 1951: 2.5, 2.3; May 20, 1951: 7.0, 6.2; May 25, 1951: 8.0; June 3, 1951: 6.0, 5.5.

The two females containing ovarian eggs on June 3, 1951, were r.e.t.a.r.ded individuals, taken along with several others that had already ovulated.

Copulation takes place in early May before the ova have grown to their full size. In the following weeks both the ova and the oviducts enlarge rapidly. Upon pa.s.sing into the oviducts, the ova a.s.sume an oval shape and are approximately 9 by 6 mm. before the alb.u.men and sh.e.l.l are added.

Deposition of a clutch of eggs probably extends over only a day or two at most, as clutches appear abruptly in the nest cavities. On only a few occasions were the females found in nest cavities with their clutches partly laid.

[Ill.u.s.tration: FIG. 8. Adult female skinks with ventral body walls removed to show reproductive organs. A. Condition in April shortly before the breeding season; the ovary (O) is still small and elongate, with the small ova forming a grapelike cl.u.s.ter; right ovary removed to expose the small bandlike oviduct (OD) beneath it.

B. Condition in late May shortly before ovulation; the greatly enlarged ovaries are removed to expose the oviducts (OD) now enlarged and convoluted for reception of the ova. C. Same stage as B, with mature ova (O) filling most of the body cavity and concealing other internal organs, I--intestine; L--liver; approximately natural size.]

s.e.xual behavior is for the most part limited to a short period of weeks in spring. In an average year in the area of the study the first two weeks of May would include the peak and the greater part of the breeding season. The "courts.h.i.+p," such as it is, and mating have been described by many observers. However none of the published accounts seems to include all the essential features in their usual sequence as observed in the present study. It has been brought out by the studies of n.o.ble and Bradley (1933:94), n.o.ble and Teale (1930:54) and Schmidt (1933:71-76) that the s.e.xual behavior of lizards has phylogenetic significance. Certain basic patterns in mating behavior are characteristic of saurian families, other traits are characteristic of genera, while certain details may be characteristic of species, or perhaps even of subspecies.

In the breeding season the adult male directs the greater part of his activities to a search for females, and finds them by both sight and scent. Observations on searching males suggest that they trail females by scent to some extent, or at least detect their presence in the general vicinity by this means. Upon discovering a female, the male pursues her with vigor and determination unless the temperature is too low, or unless he is not at the height of breeding condition. The female makes no positive response but reacts to the male's presence by fleeing, either frantically or perfunctorily, but if she is physiologically ready to breed the reaction is usually somewhat intermediate between these extremes. The first reaction of the male as he approaches the female is to touch her with his tongue, apparently receiving olfactory stimuli which are essential to the mating pattern. Rus.h.i.+ng in pursuit of the female, he then attempts to seize her in his jaws. Most often a preliminary grasp is secured on the female's tail. The female may resist vigorously, wriggling and clawing, turning upon the male to bite or to threaten with her gaping jaws. At the first opportunity the male deftly s.h.i.+fts his grip from the female's tail or hindquarters to a more anterior position, which may be as far forward as the forelimbs or may be as much as an inch behind them, a little to one side of the mid-dorsal line. The male secures his hold by pinching loose skin into a small fold. Having gained this position the male is more or less out of reach of the female's jaws, and after a brief struggle both rest quietly except for their rapid breathing, usually for a minute or more, the ventral surface of the male resting on the female's dorsal surface. The male suddenly thrusts his tail beneath that of the female. His hind leg then rests over the base of her tail and the right angle formed by the laterally projecting hind leg and the tail in each lizard aids to guide their hindquarters into position so that cloacal contact is established.

Copulation then begins immediately. The male's body may be bent in a semicircle, to one side of the female, or may be in an S-shaped loop, depending on whether or not the hemip.e.n.i.s employed is on the side opposite to that on which the female is grasped. Only one hemip.e.n.i.s is inserted, but occasionally the other may be everted also. As copulation begins the male's hind leg, flexed over the female's tail base quivers, but otherwise there is hardly any movement during approximately the first one-third of the copulatory period, and this phase may last for from one to three minutes. Then, abruptly, the male begins rhythmic, jerky flexions of the proximal portion of the tail, at the rate of approximately one per second. These tail movements are in a dorsoventral plane, and there is no perceptible movement of the body. Shortly after these movements cease, contact is broken usually at the initiative of the female, as she suddenly struggles to escape and is released either immediately or after a few seconds by the male. She then moves away, pressing her cloacal region against the ground. Her movements have become unhurried, with little or no attempt to avoid the male's attention. The male usually follows, either close behind, or straddling the female's tail or body. He may nip at her tail or body repeatedly, but without securing a grip. When the female pauses, he may come to rest with his chin or forequarters resting on her. Usually the a.s.sociation does not last more than a few minutes.

PLATE 1

[Ill.u.s.tration: FIG. 1. Habitat of _Eumeces fasciatus_ near the center of the "Skink Woods" study area on the University of Kansas Natural History Reservation, a glade with loose rocks that were used as nesting sites and shelter by many five-lined skinks.]

[Ill.u.s.tration: FIG. 2. A log on rocky slope in open woods with spa.r.s.e undergrowth, fifty feet from center of glade shown in Fig. 1.

The trees are mostly oaks (_Quercus Muehlenbergii_). The decaying log in middle foreground is much frequented by the skinks as a shelter and source of insect food.]

PLATE 2

[Ill.u.s.tration: FIG. 1. Old adult male, year-old young and hatchling in July, showing differences in size and pattern.]

[Ill.u.s.tration: FIG. 2. Adult female skink in a natural nest, with her clutch of eggs late in incubation. The nest cavity is excavated in loose soil beneath a flat rock, which was raised momentarily to expose the nest to view.]

[Ill.u.s.tration: FIG. 3. The same female and nest, with eggs in process of hatching.]