184 



CALIFORNIA ACADEMY OP SCIENCES. 



Bascanium constrictor vetustum, Townsend, Proe. U. S. Nat. Mus., 



X, 1887, p. 240. 

 Bascanium constrictor, Cope, Proc. U. S. Nat. Mus. XIV, 1891 (1892), 



p. 624 (part). 

 Zamenis constrictor, Boulenger, Cat. Snakes Brit. Mus., I, 1893, 



p. 387 (part). 



Description. — Head rather long, with flattened top and 

 rounded snout. Rostral plate large, about as high as 

 wide, hollowed below, and bounded behind by inter- 

 nasal, anterior nasal, and first labial plates. Plates on 

 top of head, a pair of internasals, a pair of prefrontals, 



supraocular and part of upper preocular of each side, 

 long frontal, and a pair of large parietals. Anterior 

 and posterior nasals distinct. Loreal well developed. 

 Preoculars normally two, but sometimes united. Post- 

 oculars two, upper a little larger than lower. Temporals 

 normally two followed by two, but may be 2-3, 1-2, or 

 1-1. Seven or eight superior and eight or nine inferior 

 labials, next to last of upper and fifth (or fourth) of 

 lower largest, third and fourth or fourth and fifth 

 superior reaching eye, first pair of inferior meeting on 

 median line. Geneials in two pair, equal or either pair 

 a little larger. Scales on body smooth, in seventeen 

 rows. Anal plate divided. Gastrosteges varying in 

 number from one hundred and sixty-three to one hun- 

 dred and seventy-nine. Urosteges in two series of 

 from seventy-nine to ninety-eight. 



