REPTILES OF THE PACIFIC COAST. 183 



Genus 33. BASCANION. 



Bascanion, B. & G., Cat. N. A. Kept., Pt. I, Serp., 1853, p. 93 (type 

 constrictor); Masticophis, B. & G., 1. c., p. 98 (type ornatus). 



The body is very long and slender, with long whip- 

 like tail. The head is distinct from the neck, large, 

 long, with flattened top and rounded snout. Its plates 

 are normal. The nasal plates are not united. There 

 are two (rarely one) preocnlars and two postoculars. 

 Temporals are normally 22. A loreal is present. The 

 scales are smooth, in fifteen, seventeen, or nineteen 

 rows, usually with two (0-3) apical pits. The anal plate 

 is divided.* Urosteges are in two series. The eye is 

 very large, with round pupil. 



Four species are known to be Californian. Young of 

 the first two are blotched, of the others, striped. 



SYNOPSIS OF SPECIES. 



a. Scales in seventeen rows. 



b. No distinct longitudinal light lines. 



c. Urosteges fewer than 100; gastrosteges fewer than 185. 



B. constrictor vetustum. p. 183. , 

 c 2 . Urosteges more than 100; gastrosteges more than 190. 



B. flagellum frenatum. p. 186. 

 b 2 . A light line along third and fourth rows of scales. 



B. laterale. p. 188. 

 a-. Scales in fifteen rows B. tseniatum. p. 190. 



58. Bascanion constrictor vetustum Baird & Girard. 

 WESTERN YELLOW-BELLIED RACER. 



Bascanion vetustus, B. & G., Cat. N. A. Kept., Pt. I, Serp., 1853, 



p. 97 (type locality San Jose, Calif.); GIRARD, U. S. Explor. 



Exped., Herp., 1858, p. 127, pi. VIII, figs. 12-19. 

 Bascanium constrictor flavivenlrls, YARROW & HEXSHAW, Surv. W. 



100*h Mer., App. NN., 1878, p. 213; YARROW, Bull. U. S. Nat. 



Mus., No. 24, 1882, p. 110 (part). 



* This plate has been found undivided in B. flagellum and its westernmost subspecies 

 B. f. frenatum. 



