13. COLUBRIDM 



tinct. Loreal rather large, with no small plate below it. 

 Preoculars two, upper much larger than lower. Postoculars 

 two, nearly equal. Temporals two followed by two. Eight 

 superior and nine or ten inferior labials, seventh upper and 

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

 pair of lower meeting on median line. Genials in two pairs, 

 posterior much larger than anterior. Scales on body smooth, 

 in 17 rows. Anal plate divided. Gastrosteges 193. Uros- 

 teges in two series of 130. Tail very long and slender. 



The color above, including the tips of the gastrosteges 

 and urosteges, is dark grayish olive brown, palest on the 

 head and tail. A single white line extends along each side, 

 on the third and fourth rows of scales, onto the base of the 

 tail. This line is narrowly bordered with black, and shows 

 slight enlargements at intervals of from four to seven scales, 

 on the anterior half of the body. The sides of the head are 

 spotted with white. The upper portions of the supralabials 

 are blackish brown. The lips, chin and throat are white, 

 without dark markings, but faintly washed with pink. The 

 anterior gastrosteges are suffused with rose pink. The 

 other lower surfaces are yellowish white with faint gray 

 cloudings laterally. 



Length to anus . . . 77+ 



Length of tail 374+ 



Remarks. — This species is closely related to both Colu- 

 ber lateralis and Coluber aurigulus. The only specimen 

 known is an adult female. 



Distribution. — This snake was found on Isla Partida, 

 Espiritu Santo Island, Gulf of California, Mexico, May 30, 

 1921. 



