Vol. I] VAN DENBURGH—SNAKES OF THE GALAPAGOS ISLANDS 347 



Dromicus occidentalis, new species. Narborough Island 



Snake 



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

 V, 1903, p. 93 (part). 



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

 teges 236 to 252; postoculars two; temporals 1 + 1 or 1+2; 

 striped (or rarely spotted), light nuchal blotches and series 

 of dark spots on tips of gastrosteges and on lower lateral 

 scales very distinct. 



Type. — Adult female. California Academy of Sciences No. 

 11488. Narborough Island, Galapagos Archipelago. J. R. 

 Slevin. April 18, 1906. 



Distribution. — Narborough Island, Galapagos Archipelago. 



Material. — Mr. Heller has recorded four snakes from Nar- 

 borough, now forming a part of the collection of Stanford Uni- 

 versity, where I have examined them. The Academy has 

 received only two from Narborough. 



Description of the type.—Htad 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 much smaller than prefrontals. Frontal 

 longer than parietal suture. Anterior and posterior nasal distmct. Loreal 

 well developed, longer than high. One preocular. Two postoculars. 

 Temporals one followed by two, or one followed by one. Eight superior 

 and ten inferior labials, sixth upper and fifth or sixth lower largest, fourth 

 and fifth upper reaching eye, first pair of lower meeting on median line. 

 Genials in two pairs, posterior a little longer, anterior touching four 

 labials. Scales on body smooth, many with pits, in nineteen rows._ Anal 

 plate divided. Gastrosteges two hundred and forty-seven. Tail incom- 

 plete. Urosteges ninety-eight, all paired. 



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

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

 postocular blotch crosses the temporal region to the side of the neck. The 

 labials and lower surfaces of the head and throat are olive gray marbled 

 with dark brown. On each side of the body there is a light yellowish-gray 

 longitudinal stripe along the sixth and seventh rows of scales. On the 

 posterior portion of the body, where there are only seventeen rows of 

 scales, this stripe drops to the fifth and sixth rows. It is continued beyond 

 the middle of the tail; but on the neck, as far as the twenty-fifth gastros- 

 tege, it is represented by a series of nine large, rounded, light spots. Along 

 the back between these light stripes is a band of dark brown, darker on the 

 scales bordering the Hght stripes. The sides are dark brown close to the 

 lateral light stripes, but become grayish oHve toward the gastrosteges. On 

 the anterior half of the body, most of the scales of the second_ row, and a 

 few of those of the first, bear central spots of dark brown. Similar small 



