VanDenburgh-The species of the genus Xantusia.pdf

7/28/2019 VanDenburgh-The species of the genus Xantusia.pdf

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THE SPECIES OF THE GENUS XANTUSIA.BY JOHN VAN DENBURGH,

Curator of the Department of Herpetology.A large number of specimens of Xantnsia vigilis and

several of Xantusia henshazvi, which I have recently col-lected, tempt me to present revised descriptions of thespecies of this genus of lizards.*Key to the Species.a^. One series of small plates (superciliaries) ever eye.

b^. Ventral plates in twelve longitudinal series.ci. A single frontal, eye large. X. vigilis.c^. A pair of frontals, eye small. X. gilberti.

V. Ventral plates in fourteen longitudinal series. X. henshaivi.a^. Two series of small plates (superciliaries and supraoculars) over eye.

Ventral plates in sixteen longitudinal series. X. riversiana.Xantusia VIGILIS Baird.Xantusia vigilis.

1859, Baird, Proc. Ac. Nat. Sci. Phila., 1858, p. 255.1893, Stejueger, N. A. Fauna, No. 7, p. 198, pi. iii, figs, la-lc.

Description.The body is subcylindrical, with veryshort limbs. The upper surface of the head is flattened,curving towards the snout. There are three folds on thethroat, the anterior connecting the ears and encircling thehead. The nostril is pierced at the junction of the ros-tral, internasal, postnasal and first labial plates. Therostral is in contact with the first labial and internasalplates. The two internasals are followed by a large sub-

* Since this paper was written, two new genera of Xantusid^eZablepsisand Amoebopsishave been proposed (Am. Nat., xxix, Aiig. 1895, p. 757),to contain Xantusia henshaivi Stejn. and Xantusia gilberti Yan D. Neitherapipears to me well founded. None of the characters alleged to be distinct-ive of Zablepsis is constant, even as a specific character of X. henshaivi;and the general scutellation and coloring of X. gilberti are so like thoseof X. vigilis as to indicate close relationship. Why these separationsshould have been made and X. riversiana still have been left in the originalgenus, I cannot comprehend.

2d Seb., Vol. V. August 28, 1895.


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524 CALIFORNIA ACADEMY OF SCIENCES.hexagonal frontonasal. Behind this are two prefontals(in contact), bordered posteriorly by the single broadfrontal and the first superciHary plates. Each of the twofrontoparietal plates forms sutures with the frontal, second,third and fourth superciharies, first supratemporal, parie-tal, interparietal and its fellow of the opposite side. Theparietals and the very large interparietal are borderedbehind by the two large occipitals. A row of small supra-temporal scutes lies along the outer edge of the occipitaland parietal plates. The two large loreals are in contactbelow with the superior labials, and above with the fronto-nasal and prefontal plates. In front of the first loreal is alarge postnasal. A series of small plates, the upper of whichare the superciharies, usually surrounds the eye. Be-tween this ring and the larger loreal are two or three smallplates. There are four or five superior and three or fourinferior labials to a point below the pupil. The eye islarge, without Hds, and with vertical pupil. Its diameteris contained about twdce in the distance from the end ofthe snout to the orbit. The obhque ear opening has avery weak anterior denticulation. The inferior labialsare in contact with the large sublabials. The first pair ofthe latter are in contact on the median hne. The back,sides, upper and posterior surfaces of the limbs, and thegular regions, are covered with subhexagonal granules.There is a series of large plates along the edge of thelast gular fold. The quadrate ventrals are in twelve longi-tudinal and twenty-seven to thirty transverse rows. Thelarge preanal plates are arranged in two series of twoeach, sometimes surrounded by a few smaller scales orgranules. The tail is conical, and covered with whorls ofsmooth scales, which are very narrow and transverselyconvex. Its length is very variable. Six to ten femoralpores form a series along each thigh.


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SPECIES OF THE GENUS XANTUSIA. 525

The ground color in different specimens varies fromsmoke gray, through many shades of yellow and brown,to clove brown. Scattered granules are dark brown orblack. At times these dark granules are so numerous asto become confluent, with a tendency to form longitu-dinal lines. In other individuals they are scarcely visible.Some specimens have heavy dotting on a very pale ground;in others the dotting is heavy on a dark ground; manyshow faint dots on a light ground; and several have fewdots on a dark ground. A yellowish line usually runsback on the neck from the outer edge of each occipitalplate. Two similar lines are sometimes present on thenape. The lower parts are creamy white, sometimesclouded with brown towards the sides. The young aver-age much darker than the adults.*mm. mm. mm. mm. mm.Suout to veut 47 44 42 37 22Tail 40t 47 61 41 24Hind limb 17 16 15^ 15 9^Fore limb 12 11 11 lOf 7Shielded part of head 9| 9 9 9 6Suout to ear 9 ' 8| 8 8 5|Snout to anterior gular fold 9 8^ 8 8 5^Snout to posterior gular fold 15 15 14 13 9Base of fifth to end of foiirth toe 6J 6 5| 5| 4

History. The first representatives of Xmitusia vigiliswere found at Fort Tejon, California, by Mr. John Xan-tus, who furnished the three specimens upon which Pro-fessor Baird based his original description, published inthe Proceedings of the Academy of Natural Sciences ofPhiladelphia for 1858. Nothing more concerning it ap-peared until May, 1893, when Dr. Stejneger recordedtwo specimens secured by the Death Valley Expeditionin 1891. Nothing has been known about its habits, and

* See remarks under Habits, p. 527.t Kegrown.


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526 CALIFORNIA ACADEMY OF SCIENCES.this very interesting species has been considered one ofthe rarest of our reptiles.

Distribution.In reality, X. vigilis is the most abun-dant lizard in the territory it has chosen for its home. Itseems to be peculiarly dependent upon the presence oftree yuccas. A glance at Dr. Merriams' map* showsthat these weird plants grow in each of the localities fromwhich the species has been recorded, viz. : Fort Tejon inthe Canada de las Uvas, and Hesperia, in California, andPahrump Valley, in Nevada.

Dr. Charles H. Gilbert and the writer collected speci-mens near Mojave, and found a portion of a cast skin atVictor, California, in November, 1893. In September ofthe following year, the writer found this species commonat Mojave and Hesperia, and secured a single specimennear Cabazon on the eastern slope of San Gorgonio Pass,California. The first three of these localities are situatedin the great Yucca arborcscens belt, which extends alongthe southwestern edge of the Mojave desert. The lastis in a small and apparently isolated grove of smaller treeyuccas, seemingly of another species.

Habits.Mojave, California, Nov. 4, 1893. About amile from the station, there is a considerable forest ofYucca arborcscens. The many trees and wind-brokenbranches, which lie decaying on the ground, afford ahome to numerous colonies of white ants, scorpions, vis-cious-looking black spiders, and several species of beetles.In a deep crack of one of these branches a small lizardwas discovered which, when caught, proved to be a youngXantiisia vigilis. Probably it had not yet learned how tohide from the day, for I have never seen another undis-turbed individual.The key to their home once discovered, the collection*N. A. Fauua, No. 7, Map 5, 1893.


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SPECIES OF THE GENUS XANTUSIA. 527of a large series of these lizards was merely a matter ofphysical exertion. Every fourth or fifth stem that was ex-amined gave up its Xantusia, and in one instance five, asmany as were previously known to collections, were foundunder a single tree.Most of the lizards were found between the bark and

the ground, but many had hidden in the thick clusters of-dead leaves, from which it was very difficult to dislodgethem. When first exposed to the light, they were darkcolored, and seemed dazzled for a moment, during whichthey made no attempt to escape. They were not at allsluggish, however, and, if not caught immediately, madefor the nearest cover as fast as their very short legs wouldpermit. This cover was often the collector, and the littlelizards either hid under his shoes, or climbed his legs,sometimes even reaching his shoulders. They showed nodesire to enter the numerous holes in the ground aboutthem, or to escape by burrowing. Put into a glass bottlethe}^ became very light colored in a few minutes, but be-gan to turn dark again immediately after sundown. Youngspecimens were numerous, and remained dark longerthan adults. Many fragments of cast skins were found,but never a whole skin in one place. The stomachs ofseveral individuals contained the wings of some smalldipterous insect, the elytra of a little brown beetle, andsome very small white bodies which resembled spiders'eggs.

Several specimens were taken alive to The LelandStanford Junior University, and kept for some months ina large glass jar in which some fine sand and pieces ofwood and bark had been placed. At first, they venturedout from their retreat only at dusk unless disturbed, butafter a few days they seemed to become more restless,and, urged perhaps by hunger, showed themselves many


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528 CALIFORNIA ACADEMY OF SCIENCES.times each day. At night, when they were always moreactive, they often climbed to the top of a piece of yuccastem placed upright in the middle of their cage. No de-sire to burrow was observed. All declined to show anyinterest in the small beetles and flies, both dead and liv-ing, which were placed in the jar, and finally becamegreatly emaciated. They were chloroformed in March,1894.Mojave, Cal., Sept. 17-18, 1894. As it was not prac-

ticable to learn by actual investigation whether or notJT. vigilis hid, during the day, among the thick-growingleaves of the living yuccas, the localities examined in1893, still clearly marked by the displaced rubbish, wereagain searched with great care. The fact that very fewspecimens were now secured in this previously-workedarea while the species was very common just outside itslimits, is evidence that the specimens found on the groundunder the dead branches were in their true diurnal home,and not mere stragglers from the living yuccas.The specimens were all caught alive and put into a

large glass bottle, but were soon killed by the heat, al-though care was taken to keep them in the shade as muchas possible. Count was kept as the lizards were put inthe bottle, and showed later that several more were takenout than had been put in. This may have been due to amistake in the record, but was more probably caused bythe birth of young after capture. The adults were after-wards carefully examined and three were found to containyoung, showing that the species is ovoviparous. One ofthe three contains fwo fetuses, the others have one each.These fetal specimens are about the size of the youngfound under the dead branches.

Hesperia, Cal., Sept. 26, 1894. Xantusias were veryabundant. Young were as numerous as at Mojave, Sept.


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SPECIES OF THE GENUS XANTUSIA. 52917-18, 1894, and the habits observed were the same asrecorded there.

Cabazon, Cal., Sept. 28, 1894. A single specimen,secured after several hours searching, was shaken fromthe dry leaves of a dead but still standing yucca abouttwo feet high.Xantusia gilberti Van D.

Xantusia gilberti.1895, Van Denburgh, Pioc. Cal. Acad. Sci., vol. v, p. 121, pi. xi.

Desa'iption. The body is subcylindrical, with veryshort limbs. The upper surface of the head is flattened,curving towards the snout. There are three folds on thethroat, the anterior connecting the ears and encirclingthe head. The nostril is pierced at the junction of therostral, internasal, postnasal, and first labial plates. Therostral is in contact with the first labial and internasalplates. The two internasals are followed by a largefrontonasal, which separates the prefrontal plates. Be-hind the latter are two large frontals. Each of the twofrontoparietal plates forms sutures with one of the fron-tals, the second and third superciliaries, first supratem-poral, parietal, interparietal, and its fellow of the oppositeside. The parietal and the very large interparietal arebordered behind by the two large occipitals. A row ofsmall supratemporal scutes lies along the outer edge ofthe occipital and parietal plates. The two large loreals arein contact below with the superior labials, and above withthe frontonasal and prefrontal plates. In front of thefirst loreal is a large postnasal. A series of small plates,the upper of which are the superciliaries, surrounds theeye.* Between this ring and the larger loreal are twosmall plates. There are five superior and four inferior*Most of these plates are united on the side of the head shown in the

figure, pi. xi.


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530 CALIFORNIA ACADEMY OF SCIENCES.labials to a point below the pupil. The eye is small,without lids, and with vertical pupil. Its diameter is con-tained about two and one-half times in the distance fromthe end of the snout to the orbit. The oblique ear open-ing has a weak anterior denticulation. The inferior la-bials are in contact with the large sublabials. The back,sides, posterior surfaces of the limbs, and the gular re-gions, are covered with smooth subhexagonal granules.These are flattened on the gular region, but convex onthe back and sides. There is a series of large platesalong the edge of the last gular fold. The quadrate ven-trals are in twelve longitudinal and thirty -two transverserows. The tail is conical, and covered with whorls ofsmooth scales, which are very narrow and transverselyconvex. There are eight and nine femoral pores.The color above is dark brownish clay, dotted withblack on single granules. A pale yellowish line, twogranules wide, runs posteriorly from each occipital plate,but is soon lost on the back to reappear over the thigh.The lower surfaces are pale yellowish white.

Snout to vent (about) 39 mm. Tail (about) 38 mm.Hind limb 14 mm. Fore limb 10 mm. Shielded part ofhead 8}4 mm. Snout to ear 8 mm. Snout to anteriorgular fold "]% mm. Snout to posterior gular fold 12)4^mm. Base of fifth to end of fourth toe ^}4 mm.

Distribution. Xantusia gilberti is known from a sin-gle specimen taken at San Francisquito, Sierra Laguna,Lower California, Mexico.Xantusia henshawi Stejn.

Xantitsia henshawi.1893, Stejneger, Proc. U. S. Nat. Mus., p. 467.

Description.The body is greatly depressed, with veryshort limbs. The upper surface of the head is very flat.There are three folds on the throat. The nostril is


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SPECIES OF THE GENUS XANTUSIA. 53Ipierced in a small scute at the junction of the rostral, in-ternasal, postnasal, and first labial plates. The rostral isbroad and rather low, bounded by the first labial, nasaland internasal plates. The two internasals are followedby a large subquadrate frontonasal, which is sometimesdivided longitudinally, behind this are two prefrontals,bordered posteriorly by the broad frontal and the firstsuperciliary plates. Each of the two frontoparietal platesis in contact with the frontal, second third and fourthsuperciliaries, first supratemporal, parietal, interparietaland its fellow of the opposite side. The parietals andinterparietal are bordered behind by the two large occipi-tals. One or more interoccipitals are sometimes present.There is a row of small supratemporals along the outeredge of the occipital and parietal plates. The two largeloreals are in contact below with the superior labials, andabove with the frontonasal and prefontal plates. The eyeis surrounded by a series of small plates, the upper fiveof which are the superciliaries. Between this ring andthe larger loreal are two small plates. There are five su-perior and three inferior labials to a point below the pupil.The eye is large, without lids, and with vertical pupil. Itsdiameter is contained about twice in the distance fromthe end of the snout to the orbit. The ear opening hasa very weak anterior denticulation. The symphysialplate is very long. The inferior labials are in contactwith the large sublabials. The first pair of the latter arein contact on the median line. The back, sides, upperand posterior surfaces of the limbs, and the gular regions,are covered with subhexagonal granular scales. Thereis a series of large quadrate plates along the edge of thelast gular fold. The quadrate ventrals are in fourteenlongitudinal and thirty-three or thirty-four transverse rows.The preanal plates are arranged in three or four rows.


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532 CALIFORNIA ACADEMY OF SCIENCES.the two median ones of the posterior series being largest.The conical tail is somewhat depressed at its base and iscovered with whorls of smooth scales, which are verynarrow and transversely convex. Eight or ten femoralpores form a series along each thigh.The ground color above is broccoli brown. On this

are numerous large irregular rounded blotches of verydark seal brown, between which run more or less con-tinuous lines of pale yellow. The upper surfaces of thelimbs and head are similarly, but less distinctly, marked.The tail is yellow with irregular blotches and half ringsof blackish seal brown. The lower surfaces are uniformyellowish white. mm. mm. mm-Sn out to vent 65 63 57Tail 83 69 66Hind limb 27 26Fore limb 16 10Shielded part of head 13 14 12JSnout to ear 13 12Snout to anterior gular fold 13 12Snout to posterior fold 21 20Base of fifth to end of fourth toe 10 9|

Distribution.Xanttisia henshawi has been found onlyat Witch Creek, San Diego County, California. Thislocality is in the chaparral belt, at an " altitude of about2,700 feet."

Habits.Here this species lives among the numerousgranite boulders, and comes out into the narrower crevicesbetween them a few minutes before dark. It is, there-fore, practicable to hunt for it only about fifteen or twentyminutes each day. If a bit of string or a straw be intro-duced into the domain of one of these lizards it will oftenbe seized, the reptile apparently mistaking it for some strayinsect.


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SPECIES OF THE GENUS XANTUSIA. 533Xantusia riversiana Cope.Xantusia riversiana.

18S3, Cope, Proc. Ac. Nat. Sci. Phila., p. 29.1889, Elvers, Am. Nat., xxiii, p. 1100.1889, Cope, Proc. U. S. Nat. Mus., p. 147.

Descri-ption. The limbs are very short, and the bod}^is somewhat depressed. The upper surface of the headis very flat. The nostril is pierced in a small scute at thejunction of the rostral, internasal, postnasal, and first la-bial plates. The rostral is broad and rather low, boundedby the first labial, nasal, and internasal plates. The twointernasals are followed by a large hexagonal frontonasal.Behind this are two prefrontals, bordered posteriorly bythe broad frontal and the first superciliar}'- and first supra-ocular plates. Each of the two frontoparietal plates is incontact with the frontal, second, third and fourth supra-oculars, parietal, interparietal, and its fellow of the op-posite side. The interparietal is bordered behind by thetwo large occipitals, which are separated from the parie-tals by two small scutes. There is a row of large supra-temporals along the outer edge of the occipital and parie-tal plates. The two large loreals are in contact belowwith the supralabials, and above with the frontonasal andprefrontal plates. The eye is surrounded by a series ofsmall plates, the upper five of which are the superciliaries.Between this ring and the posterior loreal are two or threesmall plates. A series of four supraoculars separates thesuperciliaries from the frontal and frontoparietal plates.There are five superior and four or five inferior labials toa point below the pupil. The eye is large, without lids,and with vertical pupil. The ear has a weak anteriordenticulation. The inferior labials are in contact withthe large sublabials. The first pair of the latter are incontact on the median line. The back, sides, upper andposterior surfaces of the limbs, and the gular regions, are


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534 CALIFORNIA ACADEMY OF SCIENCES.covered with flattened granules. There is a series oflarge plates along the edge of the last gular fold. Thequadrate ventrals are in sixteen longitudinal and thirty-two to thirty -five transverse rows. The large preanalplates are arranged in two or three series, edged bysmaller scales and granules. The conical tail is coveredwith whorls of smooth scales which are very narrow andtransversely convex. There is a series of from ten totwelve femoral pores along each thigh.The ground color is smoke gray or cinnamon, with

numerous irregular maculations of dark brown or black.These markings are much smaller and less numerous onthe lower surfaces. There is considerable variation inthe color pattern. One specimen has two narrow parallelblack lines, originating at the posterior edge of each oc-cipital plate, and running the whole length of the back.The space between each pair of these lines is unmarked,but the rest of the upper surface is irregularly spotted.Other specimens offer an almost perfect imitation of coarsegranitic rock.

Snout to vent io6 mm. Tail (injured) 73 mm. Hindlimb 38 mm. Fore limb 30 mm. Shielded part of head24 mm. Snout to ear 24 mm. Snout to anterior gularfold 20 mm. Snout to posterior fold 34 mm. Base offifth to end of fourth toe 14 mm.

Distribution. This largest species of the group hasbeen recorded from San Nicolas, Santa Catalina, andSan Clemente Islands, California.

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VanDenburgh-The species of the genus Xantusia.pdf