Vol. I] VAN DENBURGH—SNAKES OF THE GALAPAGOS ISLANDS 349 



gastrosteges, a character which distinguishes them from all 

 other Galapagos snakes. They seem to differ from those of 

 Albemarle and Brattle only in coloration ; and, since two speci- 

 mens show a tendency to vary in the direction of the Albe- 

 marle form, it seems best to regard those from Albemarle as 

 a subspecies. 



Dromicus occidentalis helleri, new subspecies. Heller's 



Galapagos Snake 



1903, Dromicus biserialis biserialis Heller, Proc. Washington Acad. 

 Sci, V, 1903, p. 93 (part). 



Diagnosis. — Scale-pits present, scales in 19 rows; gastros- 

 teges more than 236; postoculars two; temporals 1-1-2 or 2-f2, 

 spotted, no longitudinal light stripes; no series of definite 

 rounded blackish spots on lateral scales of first and second 

 rows; light nuchal markings much less prominent, and dark 

 spots on tips of gastrosteges absent or less distinct than in the 

 Narborough form. 



Type. — Male. California Academy of Sciences No. 10280. 

 Brattle Island, Galapagos Archipelago. J. R. Slevin. October 

 30, 1905. 



Distribution. — Albemarle and Brattle Islands, Galapagos 

 Archipelago. 



Material. — Mr. Heller has recorded one specimen from near 

 Cape Berkeley, Albemarle, which now is No. 4977 of the 

 Stanford University collection. The Academy has received 

 two from Brattle. 



Description of the type. — Head rather broad, with flattened top and 

 rounded snout. Rostral plate large, much broader than high, hollowed 

 below, and bounded behind by internasal, anterior nasal, and first labial 

 plates. Plates on top of head are: a pair of internasals, a pair of pre- 

 frontals, supraocular and part of preocular of each side, a frontal, and a 

 pair of large parietals. Internasals smaller than prefrontals. Frontal 

 longer than parietal suture. Anterior and posterior nasals distinct. Loreal 

 well developed, little longer than high. One preocular. Two ppstocukrs. 

 Temporals one followed by two. Eight superior and ten inferior labials, 

 sixth upper and fifth lower largest, fourth and fifth upper reaching eye, 

 first pair of lower meeting on median Hne. Genials in two pairs, posterior 

 longer, anterior touching four or five labials. Scales on body smooth, many 

 with pits, in nineteen rows. Anal plate divided. Gastrosteges two hundred 

 and forty. Tail complete. Urosteges one hundred and twelve, the first to 

 third, seventh to eleventh, and fourteenth and fifteenth not divided. 



The top of the head is olive brown dotted with olive gray. A light 

 brown band extends from the rostral plate to the eye, and a brown post- 



