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 the 

 species 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 very 

 short limbs. The upper surface of the head is flattened, 

 curving towards the snout. There are three folds on the 

 throat, the anterior connecting the ears and encircling the 

 head. The nostril is pierced at the junction of the ros- 

 tral, internasal, postnasal and first labial plates. The 

 rostral is in contact with the first labial and internasal 

 plates. The two internasals are followed by a large sub- 



* Since this paper was written, two new genera of Xantusid^e — Zablepsis 

 and Amoebopsis — have been proposed (Am. Nat., xxix, Aiig. 1895, p. 757), 

 to contain Xantusia henshaivi Stejn. and Xantusia gilberti Y an D. Neither 

 apipears 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 those 

 of X. vigilis as to indicate close relationship. Why these separations 

 should have been made and X. riversiana still have been left in the original 

 genus, I cannot comprehend. 



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



