28 Dr. A. Giinther on new Species of Snakes 



scarlet during life. Ventrals 151 (136) ; anal 1/1 ; subcau- 

 dals 68. 



Hydr^thiops (g. n. Natric. vel Homalops.). 



Body stout, cylindrical ; form of the head as in Homalopsis. 

 A single anterior and two posterior frontals. Nostrils on the 

 upper surface of the snout^ narrow slits between two nasals. 

 Scales keeled, short, in twenty-three series ; anal and sub- 

 caudals divided. Loreal present. Maxillary teeth in an un- 

 interrupted series, slightly increasing in length posteriorly, 

 numerous and closely set ; none grooved. 



This is another form intermediate between the Natricidce 

 and Homalopsidw. Having entirely the physiognomy of the 

 latter, it differs by its dentition. From Atretmm and Limno- 

 phis it is distinguished by the position and form of the nos- 

 trils, from Tretanorhinxis and Neusterophis by the single an- 

 terior frontal. 



Hydrcethiops melanogaster. PI. III. fig. G. 



The single anterior frontal is an isosceles triangle, touching 

 the rostral ; posterior frontals small, but rather larger than the 

 anterior. Vertical not twice as long as broad, with parallel 

 outer edges, and with a right angle behind ; occipitals as long 

 as the vertical and posterior frontals together, rounded behind. 

 Loreal large, longer than deep, with the lower posterior angle 

 rather produced. One prteocular, extending to the upper sur- 

 face of the head, but not reaching the vertical. Two post- 

 oculars, the lower of which is small. Nine or ten (eleven) upper 

 labials, the fourth and fifth or the fifth and sixth entering the 

 orbit. Temporals 1 + 2 + 3, the anterior in contact with the 

 upper postocular. Chin-shields two pairs, the anterior longer 

 than, and produced between, the posterior. Cleft of the mouth 

 bent upwards behind ; a groove behind the eye between the 

 labials and temporals. Eye small. Ventrals 153 ; anal 1/1 ; 

 subcaudals 43. Upper and lower parts of a uniform shining 

 black ; a reddish or yellowish band runs along the side of the 

 head and trunk, along the three or two outer series of scales, 

 becoming narrower behind. 



Gaboon. 



The largest of four examples is 24 inches long, tail 4 inches. 



West Africa appears to be much richer in freshwater snakes 

 than was formerly believed. We now know 



1. Tropidonotus ferox, from Fernando Po. 



2. Neusterophis Imvissima (exact locality unknown). 



3. Limnophis hicolor^ from Angola. 



4. Hydrcethiops melanogaster, from the Gaboon. 



