648 Bulletin American Museum of Natural History [Vol. XLY1 



The distinctness of this species rests 

 primarily on the convex frontal region of the 

 head, which is accompanied by an enlarge- 

 ment of the scales in the same area, and the 

 low number of femoral pores. The tail is 

 rather short, ranging from .54 to .56 of the 

 Fig.6. Lateral view of the head total, mean .55. The length of the hind leg 



of Callisaurus splendidus Dickerson, • i • c nn ± r\n e ±^ 



\ m n h No 5373 x 2 ls moderate, ranging from .86 to .98 of the 



length from snout to vent, mean .92. The 

 occipital is in contact with the supraorbital semicircles in seven out of 

 eight specimens. 



Callisaurus ventralis inusitatus (Dickerson) 

 Plate LI, Figure 1; Plate LII, Figure 2 

 Callisaurus inusitatus Dickerson, 1919, p. 465. ' 



Callisaurus ventralis ventralis (part) Stejneger and Barbcur, 1917, p. 47. 

 Range. — Tiburon Island and adjacent part of Sonora, Mexico. 



Twenty-nine specimens of a species of Callisaurus were collected 

 on Tiburon Island by the Albatross Expedition. 



In spite of the fact that I have no actual intergrades between this 

 form and the Arizonan C. ventralis, the nature of the characters used 

 to distinguish it from ventralis ventralis on one hand and ventralis gabbii 

 on the other is such that I prefer to give it subspecific rank. 



The series before me is rather strikingly different from C. ventralis 

 ventralis in habitus, being much more slender bodied and longer limbed. 

 This character does not appear in its real value in a tabulation of 

 measurements, C. ventralis ventralis with the same length of body and tail 

 being much heavier. The length of the hind leg is variable but averages 

 much longer than in the Arizonan specimens, while the femoral pores, 

 averaging 18, distinguish it from the form in southern California and 

 Lower California (C ventralis gabbii). 



The character of the union of the black lateroventral bands in- 

 feriorly in the males is invariable in the present series. 



Callisaurus ventralis gabbii Cope 

 Plate LI, Figure 1 

 Callisaurus ventralis gabbii Cope, 1900, p. 272. 

 Callisaurus plasticus Dickerson, 1919, p. 466. 2 

 Callisaurus carmenensis Dickerson, 1919, p. 465. 3 



'Type: U. S. N. M. No. 04256. Paratvpes: C. S.N. M. Nob. 04520-29, A. M. N. H. Nos. 5317-19, 

 5322. 5325-37, 5346. 



?Type: U. S. N. M. No. 64255. Paratvpes: U. S. N. M. Nos. 64531-42; A. M. N. H. Nos. 5308- 

 14, 5346-48, 5350-54, 5357-60, 5381-87. 



'Type: U. S. N. M. No. 64253. 



