Vol. 35, pp. 219-220 October 17, 1922 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



TWO NEW SOUTH AMERICAN SNAKES. \ 



BY E. R. DUNN. 



While going over some of the South American snakes in the 

 Museum of Comparative Zoology, I happened upon two which 

 seem as yet undescribed. As will be apparent their generic 

 assignments are rather a problem, although their direct specific 

 relations are easily determined. 



Dromicus amazonicus, sp. n. 



Type.—M. C. Z., No. 2820, Santarem, Brazil. 



Scales 17; ventrals 152, anal divided; caudals 75. Eight upper labials, 

 4th and 5th entering eye; loreal longer than high; one pre- and two postocu- 

 lars; temporals 1-2; internasals as long as broad, frontal longer than its 

 distance from tip of snout, shorter than the parietals; latter longer than 

 their distance from the internasals; anterior chin shields longer than pos- 

 terior; olive brown above, white below and on the first two scale rows; dark 

 spots on some of the scales of the 7th and 8th rows, forming two dorsal dark 

 lines which disappear on the tail; upper labials and throat white with dark 

 mottlings; a pair of white spots on the nape. Total length 250 mm., tail 

 55 mm. 



Apparently allied to Rhadinea binotata, Werner, also from Brazil, but 

 hinotata has the posterior chin shields longer; a dark stripe between the two 

 light flecks on the neck; and the sides, inclusive of the ends of the ventrals, 

 are olive green. 



Van Denburgh (1912 Proc. California Acad. Sci. (4) I p. 327) has pointed 

 out the comparative uselessness of the scale pits for defining genera in this 

 group of snakes. It then becomes exceedingly doubtful whether Rhadinea, 

 Aporophis, Leimadophis (Liophis) and Dromicus (Alsophis), can be main- 

 tained as separate genera. There are doubtless several natural groups 

 within this mass of some 110 snakes, but until better characters are found 

 it is at least unsafe to describe a snake in one of these genera without care- 

 fully considering the species of the others. Dromicus is the oldest tenable 

 name and is not preoccupied by Dromica. 



As examples of the danger of trusting too readily to the generic divisions 

 in this group it is worth while to mention — 



37— Pboc. Biol. Soc. Wash., Vol. 35, 1922. (219) 



