160 



CALIFORNIA ACADEMY OF SCIENCES. 



tapering tail, and little if any constriction at neck. 

 The snout is long, rounded, and much depressed. The 

 head-plates are normal except in the union of the an- 

 terior and posterior nasals. One preocular, two post- 

 oculars, and a loreal are present. Temporals are normally 

 1-2. The scales are smooth, in fifteen rows. The anal 

 plate is divided and the urosteges are in two series. The 

 eye is rather small, with round pupil. 



48. — Chionactis occipitalis (Hallowell). Desert Snake. 



Rhinostoma occipitale, Hallow., Proc. Ac. Nat. Sci. Phil., VII, 1854, 



p. 95 (type localitj' Mojave Desert). 

 Lamjyrosoma occipiicde. Hallow., 1. c, VIII, 1856, p. 310; Hallow., 



U. S.Pac. K.K.Surv., X, 1859, pt.IV, p. 15, pi. IV, figs. 2a-2c; 



Kenn., U. S. Mex. Bound. Surv., Ill, Kept., 1859, p. 21, pi. XXI, 



fig. 1; BocouRT, Miss. Sci.au Mex., Kept., 9eLivr.. 1883, p. 558, 



pi. XXXIV, fig. 6-6e. 

 Lamprosomaannulatum, Baird, U.S. Mex. Bound. Surv., Ill, Kept., 



1859, p. 22, pi. XXI, fig. I (type locality Colorado Desert). 

 Chionactis occipitalis, Cope, Proc. Ac. Nat. Sci. Phil., 1866, p. 310; 



Cope, Proc. U. S. Nat. Mus., XIV, 1891, p. 605. 

 Contia occipitalis, Garman, Mem. Mus. Cornier. Zool., VIII, 3, 1883, 



p. 91; Boulenger, Cat. Snakes Brit. Mus., II, 1894, p. 266. 



Def^cription. — "Head small, of same breadth poste- 

 riorly as neck, depressed in front; snout rounded; rostral 



plate large, excavated 

 below, presenting a tri- 

 angular shape above and 

 in front where it forms 

 the extremity, of the 

 muzzle ; internasals 



smaller than prefrontals, their inner margins much 

 shorter than their external, which are in contact 

 with the upper margins of the nasal plates; the pre- 

 frontals are more or less pentangular in shape, the 

 posterior margin of each in contact with the ante- 

 rior margin of the antocular, the supraocular, and 



