Robert C. Stebbins

Activity Changes in the Striped Plateau Lizard with Evidence on Influence of the Parietal Eye

The effect of a regular 9-hour light-heat period on adult striped plateau lizards (Sceloporus virgatus) was studied over a period of 21 months. Eighteen males and 40 females were used. The parietal eye of half the animals of each sex was impaired. The lizards were kept in runways with sand in which they could bury; 150-watt lights provided a light-heat gradient. A wide range of light and heat was available during the period of illumination. The experiment was conducted in a temperature control room at 16-17?C; humidity changes were slight. There were marked changes in the frequency with which the lizards were seen on the surface. Since the changes were out of phase with one another and with those of animals in the field, they are thought to be endogenous. Parietal eye impairment caused increased use of bright light and selection of a lower body temperature for burial, but there was no effect on frequency of exposure on the surface or viability.

The Effect of Parietalectomy on the Thyroid and Gonads in Free-Living Western Fence Lizards, Sceloporus occidentalis

Adult western fence lizards (Sceloporus occidentalis) at Foss Valley, Napa County, California, were parietalectomized and sham-operated in equal numbers in the fall of 1968, marked, and returned to places of capture. In the spring of 1969, following hibernation, behavior of the two surgical groups was noted for approximately two months and the animals were then sacrificed for study of the thyroid and gonads. Parietalectomized lizards of both sexes had more active thyroids, as measured by follicular epithelial cell height, than sham-operated ones. Parietalectomized females had heavier ovaries and higher ova counts than controls. No differences were found between the two groups in reproductive activity of males. Parietalectomized lizards of both sexes exposed themselves to sunlight more frequently than controls, which may explain the physiologic changes noted.

The Effect of Parietalectomy on Testicular Activity and Exposure to Light in the Desert Night Lizard (Xantusia vigilis)

The effect of removing the parietal eye (parietalectomy) on testicular activity and exposure to light was studied in captive Xantusia vigilis during their period of testicular recrudescence. Half the animals were parietalectomized and half were sham-operated. Each animal was kept in a separate cage that provided a continuously available range of light from total darkness to full illumination. The lizards were thus free to expose themselves to light at any time during the experiment. Temperature in the cages was held constant at 27? C. The parietalectomized lizards exposed themselves to light more frequently than the controls and at peak performance were observed a third more often in the lighted portion of their cages. Evidence concerning the condition of their reproductive tracts suggested that their reproductive cycle accelerated and that at the end of the experiment many individuals had already completed one cycle and had begun a second.

A New Species of Plethodontid Salamander from the Jemez Mountains of New Mexico

T account for the occurrence of the lungless salamander Plethodon hardii in the Sacramento Mountains of southern New Mexico, one may assume that the species or its predecessor arrived there via the Rocky Mountains. The country adjacent to the Rockies, except well to the north, is today, so far as is known, uninhabited by these amphibians and probably long has been unsuited to them. It seems plausible that at one time plethodontids existed across the northern part of the continent, dispersing westward from an eastern center of differentiation (Dunn, 1926: 11 and 12). From this northern reservoir one may surmise that they made their way southward, and that at some time they became widespread in the Rockies. Only two species, Plethodon idahoensis of the northern part of the Rocky Mountains in Idaho and P. hardii at the extreme southern end, have been described. It has seemed likely to us that other remnants of a once widely distributed Rocky Mountain fauna might yet exist. On August 14, 1949, motivated by the foregoing idea, we visited the Jemez Mountains, Sandoval County, New Mexico. At the same time we wished to check on the possible occurrence of Eurycea multiplicata (?), reported by Dunn (1926: 316). We failed to find Eurycea but discovered, instead, a Plethodon, which we here describe. We have determined that the material, USNM 42921-2, upon which the record of Eurycea was based, is of this new species.

Observations on Laying, Development, and Hatching of the Eggs of Batrachoseps wrighti

N April 1, 1948, an adult female Batrachoseps (=Plethopsis) wrighti, heavily laden with eggs, was obtained at the type locality, 8.7 miles southeast of Sandy, Clackamas County, Oregon. Since the eggs of this salamander were unknown, she was brought into the laboratory in the hope that oviposition could be observed. She was placed in a gallon glass container with a metal screw lid. A single paper towel, wetted with distilled water, was put into the bottom of the jar. The container with the salamander was kept in a dark room where the temperature was maintained continuously at approximately 12? C. Thermal data on field animals suggested that this temperature might be commonly experienced under natural conditions. After nearly one month in captivity, the salamander still retained her eggs. Dispairing of obtaining them without stimulation, I employed the pituitary implantation technique described by Noble and Richards (1930) and thereby oviposition was initiated. Implantation was done as follows. On May 25, 1948, at 3:40 P.M., I implanted a single whole pituitary gland freshly removed from an adult male Hyla regilla. The salamander was anesthetized in chlorotone (1 part saturated solution to 3 parts water), whereupon a small incision was made in the skin of the gular area. The Hyla pituitary was removed with forceps and was transferred directly to the site of the incision. A dissecting needle was used to force the gland into place beneath the the skin. By the time the salamander recovered from the chlorotone, several hours later, coagulation of blood and lymph at the site of the operation prevented displacement of the implant. About 42 hours later, a second Hyla pituitary was implanted. On June 1, 1948, at 9:00 A.M. the first egg was laid. Laying was completed June 2 at around 9:00 P.M., approximately 36 hours after the beginning of oviposition. Eleven eggs were deposited. Their chronology was as follows: June 1-3 eggs laid at approximately 21/2 hour intervals, around 9:00 A.M., 11:30 A.M., and 2:00 P.M.; June 2-8:40 A.M., 7 eggs present with the 8th emerging; 1:30 P.M., 9th egg emerging; 7:15 P.M., 10 eggs; 9:00 P.M., 11 eggs. The brief description of the eggs (Stebbins and Lowe, 1949), may now be supplemented [see Fig. 1, (1)]. The most striking characteristic of the eggs is their size. After some hours on the wet paper towel of the container, the jelly layers had swelled enormously, measuring, to their outer surfaces, 9 to 10 mm. The female salamander, only about 5 mm. in greatest width, seemed incredibly small to have deposited such large eggs (see Fig. 2, A). When laid, the jelly layers were thin and the vitellus was elastic, permitting its passage, with some temporary distortion, through the cloacal aperture. The vitellus, or egg proper, was unpigmented, between Cream Color and Pale Ochraceous-Buff.1 It rotated with the animal pole uppermost when the egg

The Systematic Status of Plethopsis with a Discussion of Speciation in the Genus Batrachoseps

This genus is related to Plethodon from which it differs in having only four toes, vomerine and parasphenoid teeth often forming a continuous series, incompletely ossified parietals and frontals and multiple testes in large males. From Hemidactylium it differs in lacking the basal constriction of the tail, in the condition of the parietals and frontals, in the number of costal grooves, the multiple testes and the lack of a marked sexual dimorphism. It resembles Batrachoseps in the incompletely ossified parietals and frontals but differs in the possession of two premaxillae, larger hind limbs, in the number and disposition of the teeth, multiple testes and lack of worm-like body.