Dunn — Two New Crotaline Snakes from Western Mexico. 215 



Range. — West coast of Mexico in Sinaloa and western Durango. 



Type. — United States National Museum, No. 46,486. Plumosas, Sinaloa, 

 Mexico; July 19, 1897. Nelson and Goldman collectors. 



Description of type specimen. — Scales in 27 rows, the first smooth, the rest 

 keeled. Ventrals 176, anal entire, caudals 44 undivided. Rattle very 

 small, seven rings and button measuring 12 mm. long and four mm. wide. 



Upper surface of snout with one large pair of internasals and a row of four 

 prefrontals, the two outside ones in contact with internasal and surpraocular 

 — canthus rostralis distinct. Supraocular shields narrower than space be- 

 tween them, smooth — 7-9 scales between supraoculars, and 10-13 scales in 

 contact with them. Two scales between eye and nasal. Eye separated 

 from labials by three series of scales. Rostral in contact with nasal. Supra- 

 labials 14 L, 15 R; lower labials 16, the first pair produced backwards 

 in contact with each other behind the symphysial and with the third lower 

 labial, thus cutting the second lower labial from the chin shields. Color 

 grayish-brown; a series of 40 darker brown, black-edged dorsal rhombs (the 

 first of which is split on the neck) three scales long and on seven scale rows. 

 Alternating with these on the ninth scale row a dark spot covering about 

 one scale. In the same transverse plane as the dorsal rhombs dark spots 

 covering about one scale in each of the third, fourth and fifth rows. Alter- 

 nating with these a dark spot on a scale of the first row and the tip of the 

 preceding gastrostege. Belly grayish marbled with black. Tail dull brown 

 with indistinct dark cross-bands. Head flecked above with black, a darker 

 brown blackedged band from beneath eye to angle of jaw. Lower half of 

 upper labials white. Throat white, a dark spot below angle of jaw and tip 

 of lower jaw grayish. 



Variation. — A smaller specimen with a rattle consisting of button alone — 

 United States National Museum, No. 46,460, with the same data, shows 

 few minor variations. On one side four series of scales separate eye from 

 labials. The second lower labial is narrowly in contact with the chin shield, 

 thus separating the first labial from the third. The scale counts for this 

 specimen are V 174, C 41, Sc 27, L 14/13-14. Same pattern as type. 

 Forty-four dorsal rhombs, two elongated black spots on occiput, a dark spot 

 which is partly on the posterior end of the supraocular and a similar spot 

 partly on the anterior end of the same scale. 



Dimensions. — Type No. 46,486. Total length, 590 mm.; tail except 

 rattle 77 mm. No. 46,460, total length, 284 mm., tail except rattle, 33 mm. 



Remarks. — This snake scarcely needs comparison with any described 

 form. The subcaudals are more in number than in any of the described 

 species. The shape of the tail and the minuteness of the rattle are charac- 

 ters which scarcely stand out on paper but which are very striking in the 

 specimens. The peculiar shape of the first lower labial is unique, also. 

 In pattern stejnegeri is remotely similar to the snakes of the triseriatus- 

 pricei group, but even here the relationship is not close. 



Boulenger (Cat. Snakes British Museum III, p. 580) records a specimen 

 of C. tigris from Ventanas, Durango, Mexico, on the western slope of the 

 Sierra Madre about 15 miles from the Sinaloa border and undoubtedly in 



