1893.J ^45 [Cope. 



of the rostral plate. Rostral plate a little visible from above ; internasals 

 subquadrate ; frontal about as wide at middle as each superciliary, and a 

 little shorter than the parietals. Loreal longer than high ; one preocular, 

 which does not reach the frontal. Two postoculars, the superior the 

 longer, and half bounded posteriorly by the parietal. Temporals, 2-2, 

 the anterior elongate. Superior labials nine, fourth, fifth and sixth in 

 orbit ; all longer than high, except the second, which is quadrate, and the 

 seventh, which is subtriangular. The eighth is much the longest. Infe- 

 rior labials ten ; geneialslong, the posterior the longer. Gastrosteges 155 ; 

 anal 1-1 ; urosteges 145. 



Color above, brown ; below, cream color. Small rusty spots appear on 

 the sides throughout the length, at intervals of two scales, on the fourth 

 or fourth and fifth rows ; and they are bounded posteriorly by a 

 small deep brown spot. From the middle of the body posteriorly, the 

 first three rows of scales are paler than those above them, and the third 

 row carries a small black spot on each scale. These spots become conflu- 

 ent into a narrow stripe, which is distinct on the posterior fourth of the 

 body and on the side of the tail. The scales of one and two rows above 

 this stripe are paler than those of the median dorsal region. Head uni- 

 form brown, upper lip and below uniform yellowish. 



Total length 815 mm.; total length of tail 352 mm.; length of head to 

 canthus oris, 20 mm. ; interorbital width 8 mm. 



Boruca, No. 336, adult; Buenos Ayres, No. 336, young. In the young, 

 the anterior half of the body presents the cross-bars characteristic of the 

 young of this genus. On the posterior half the cross bars are broken up 

 into a series of small dark spots on each side, and a narrow longitudinal 

 lateral stripe below them, as has been already shown t!D exist in the adult. 



Synchalinus cokallioides, gen. et sp. nov. 



Char. gen. — Teeth equal, smooth. Scales with two terminal fossae. 

 Body compressed, gastrosteges sharply angulated near extremities ; head 

 distinct. Pupil round. Anal plate entire ; subcavidals in two rows. 

 Cephalic plates normal except that the nasals and loreal are fused into a 

 single, elongate plate. 



In this genus we have apparently a colubrine snake of arboreal habits, 

 which has assumed a boieform character rather than that characteristic of 

 the tree-snakes proper. In the thin scales and fusion of lateral head 

 plates we have a resemblance to the little known genus, Amastridium, but 

 that form is of entirely terrestrial habit. 



Char, specif. — This snake has at first sight considerable resemblance to 

 some of the color varieties of the tree- boa, Corallus hortulanus. In its 

 color tints and patterns it also resembles the Spilotes luiiulatus m. The 

 body and tail assume a coiled attitude in spirits like the species of Coral- 

 lus, and the sharp angles of the gastrosteges show that the habits are 

 similar. 



Scales in twenty-three rows, the first and several median composed of 



PROC. AMER. PHILOS. SOC XXXI. 142. 2 R. PRINTED DEC. 30, 1893. 



