Vol. I] VAN DENBURGH—SNAKES OF THE GALAPAGOS ISLANDS 339 



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

 snout. Rostral plate large, a little 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 prefrontals, supra- 

 ocular and part of preocular of each side, a frontal, and a pair of large 

 parietals. Internasals much smaller than prefrontals. Frontal slightly 

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

 well developed, longer than high. One preocular. Postoculars three. 

 Temporals two followed by two. Eight superior and nine 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 five labials. Scales on body 

 smooth, without pits, in seventeen rows. Anal plate divided. Gastrosteges 

 two hundred and seven. Tail complete. Urosteges one hundred and thir- 

 teen, all paired. 



The color above is deep olive brown becoming paler posteriorly and 

 seal brown toward the head. A light dorsolateral band, about two scales 

 wide, arises on the upper postocular, crosses the parietal, and continues 

 along the fifth and sixth rows of scales. This yellowish-brown band 

 becomes less distinct on the middle third of the body and nearly obsolete 

 posteriorly. The tail is unicolor, olive, becoming yellowish olive toward 

 the tip. The dark brown postocular or temporal bar is continuous with 

 the brown band on the side of the neck. There is no light nuchal blotch. 

 The labials are yellowish white marked with blackish olive. The first and 

 second rows of scales on the neck are whitish, marked anteriorly with a 

 row of blackish spots, continuous with a similar row formed of one spot 

 near the lateral extremity of each gastrostege from about the fourth to 

 twenty-second. The lower surfaces are yellowish dotted or clouded with 

 grayish olive. 



Length to anus, 518 mm. 



Length of tail, 217 mm. 



Variation. — All the males have seventeen rows of scales, 

 while all of the females have nineteen rows. Careful search 

 of every specimen failed to disclose any scale-pits except in 

 the case of No. 9306, on which one scale showing a single 

 pit was found. The gastrosteges range in number from two 

 hundred and three to two hundred and fourteen. The uros- 

 teges in specimens with complete tails vary from ninety-four 

 to one hundred and fourteen in males and from ninety-one to 

 one hundred in females. All of the urosteges are paired except 

 in the specimen from Gardner Island, which has two undi- 

 vided. The postoculars are always three. The temporals 

 normally are 2-1-2, and the supralabials eight. The following 

 table shows the scale-counts. In the urostege column c indi- 

 cates that the tail is complete, while -|- is affixed to counts 

 when the tip of the tail is missing. 



January 15, 1912 



