-■1 7U'iv genus of Strpinis, i^v. 179 



very small, but are separated in the middle by tlie gray colour, 

 which is irregularly punctuated with blackish brown points ; 

 while the lower part of the abdomen, for about '3l inches, is 

 almost entirely black, having only here and there small white 

 spots in an irregular order: but every plate has two of them 

 running transversely across it. The lower plate, which covers 

 the anus, and which is semi-circular, is more white, having a 

 triangular black spot towards the centre, and black points to- 

 wards the circumference. The subcaudal plates are all black, 

 while the scutella are white ; some entirely, others having black 

 spots at their base. The abdominal plates are more or less 

 iridescent, reflecting, when seen in a certain position in regard 

 to the light, a sky-blue colour. 



From this description, it is evident that the Acontias cannot 

 belong to any of the established genera. From the Ccnchris, 

 Daud. it is distinguished by the arrangement of the subcaudal 

 plates, and the aperture between the nostrils and the eye. — 

 According to Daudin the double subcaudal plates in the Cen- 

 chris are at the base of the tail ; the reverse is found in our 

 reptile. Also the arrangement of the plates at the head is dif- 

 ferent in the Cenchiis. The figure given by the author, men- 

 tioned above, and concerning which he says, ^^ que fai fait 

 peindre avec une gra?ide exactitude, et sous mes yeiix,'''' (tom. v. 

 p. 31) does not resemble the Acontias. In the Cenchris the 

 large plates of the head terminate in two large plates. I wish 

 to make the difference betvveen the Cenchris moJceson of Daud. 

 and our new genus evident, because the following species is 

 known in the west by the name of highland moccason. 



The aperture between the nostrils and eyes assimilate the 

 Acontias to the genus Crotalus ; but the arrangement of the 

 subcaudal plates and the rattles at the tail are sufficient to dis- 

 tinguish them from each other. 



The arrangement of the subcaudal plates seems to be the 

 ssiine in the Hurria ; but that genus has no venomous fangs, 

 and differs in several other respects. 



