Vol. I] VAN DENBURGH— SNAKES OF THE GALAPAGOS ISLANDS 337 



1892, Orophis biserialis Garman, Bull. Essex Inst., XXIV, 1892, p. 85 

 (part). 



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

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



Diagnosis. — No scale-pits; scales in 19 rows; gastrosteges 

 209; urosteges 108 to 110, all paired; postoculars three; tem- 

 porals usually 2+2 ; spotted. 



Type. — British Museum. Charles Island, Galapagos Archi- 

 pelago. Charles Darwin. 1835. 



Distribution. — Charles and Gardner-near-Charles islands, 

 Galapagos Archipelago. 



Material. — Only two specimens of this species are in collec- 

 tions. These are : the type, a young specimen from Charles 

 Island, preserved in the British Museum, and one female speci- 

 men from Gardner Island — No. 9448 of the Academy collec- 

 tion. 



Description of No. 9448. — Head rather long, with flattened top and 

 rounded snout. Rostral plate large, a little broader then 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 nasals distinct. Loreal 

 well developed, longer than high. One large preocular with a very small 

 one below it on each side of head. Postoculars three. Temporals two 

 followed by two or three. Eight superior and ten inferior labials, sixth 

 upper and sixth or seventh lower largest, fourth or 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 nineteen rows. Anal plate divided. Gas- 

 trosteges two hundred and nine. Tail complete. Urosteges one hundred 

 and eight, all paired. 



The color above is a pale grayish olive. A dark streak runs back from 

 the eye. The infralabials and the posterior superior labials are blotched 

 with yellowish white. There is a yellowish-white blotch on each side of 

 the nape. There are no traces of longitudinal bands on the body, but along 

 the back is a series of irregular dark brown cross bars or alternating spots. 

 A few indications of similar spots may be made out on the sides. The tail 

 is unspotted except near its base. The lower surfaces are creamy white, 

 plentifully dotted or clouded with dark gray. There are no very distinct 

 blackish-brown lateral spots on the anterior gastrosteges. 



Length to anus, 590 mm. 

 Length of tail, 220 mm. 



Variation. — The type specimen from Charles Island has 

 two hundred and nine gastrosteges, one hundred and ten uros- 



