SYNOPSES ANi) DESCRIPTIONS. 



12^ 



blotches of brown or black, separated by narrow spaces of light color. 

 Lower surface yellow, somewhat clouded posteriorly. Head spotted with 

 dark on the parietal region, with a ti'ansverse band of dark in fi'ont of the 

 supraciliaries through the eye to the hinder labial. Description fi'om Bra- 

 zilian specimens. Species said to occur in Southern Mexico. 



Var. STENOPHRYS. 

 Lachesis stenophry.s Cope, 1875, Batr. and Rept. Costa Rim, 152. 



Muzzle short, depressed; rostral an equilateral triangle. Crown-scales 

 flat, hexagonal, faintly keeled. A trapezoid plate in front of the large 

 superior preocular. Four rows of scales between labials and orbits. 

 Labials nine, third largest, second low and not bounding the pit. Pit 

 bordered by three plates ; upper narrow, in contact with both preoculars ; 

 lower wider, above the third labial; anterior above the second labial. 

 Supraciliaries narrow, separated by twelve series of scales. Infralabials 

 thirteen, first large. Submentals one pair, truncate in front, narrowly 

 rounded behind. Scales in 36 rows, ten on each side of the median line 

 with a central tubercle. Ventrals 200. Subcaudals 32 pairs, plus 17 

 transverse series of small ones under the extremity of the tail, terminal 

 spine well developed. 



Brown, with twenty-three reddish -brown rhombs on the median rows; 

 the lateral angles are dark spots on the flank, sometimes isolated. On the 

 middle of the body the rhombs have pale centers, posteriorly they are 

 darker, irregular, confluent into a zigzag band. Tail dark brown, with 

 narrow light cross-bands. Lower surfaces greenish -yellow, except the 

 throat and chin, which are white (in spirits). A black band from the eye 

 above the labials, broken upon the neck into a series of spots. Top of 

 head uniform brown. Total length 0", 495; tail 0"", 50. (Cope.) Sipurio. 



TRIGONOCEPHALUS. 



Oppcl, 1811. 



Elongate fusiform, back slightly compressed; head large, distinct from 

 the neck, depressed, triangular, broad behind, pointed in front; muzzle 

 prominent, angular; tail short, tapering to a point. Crown-shields small, 

 scale -like. Eye moderate, pupil vertical. Scales keeled. Anal entire. 

 Subcaudals two-rowed, rarely simple. Mexico to Patagonia. 



