Nov. 1847.] 319 



of the Silurian rocks of the south mountains, and which is 

 believed to be of the same age as the so-called Potomac marble. 



r Meeting for Business, Nov. 20, 1847. 



Vice President Morton in the Chair. 



The Committee on Dr. Hallowell's paper, on the Horned 

 Viper of Western Africa, reported in favor of publication : 



On the Horned Viper of Western Africa. 



By Edward Hallowell, M. D. 



Cerastes, Wagler. 



Cerastes* nasicornis. 



Syn. Coluber nasicornis. Shaw, General Zoology, p. 198. 



Characters. Head short and thick, two horns upon the snout, mouth 

 large ; a series of oblong quadrilateral bands upon the back, margined with 

 triangular spots of black ; a row of dark colored blotches upon each side of 

 the animal in contact with the abdomen ; between these and the triangular 

 lateral blotches, other triangular dark colored spots with their bases toward 

 each other ; tail short. 



Descriptions. Physiognomy very repulsive ; head short and thick, de- 

 pressed, presenting two horns, each four lines in length upon the 

 snout ; opening of the mouth large, extending to within five lines of the 

 posterior margin of the occiput ; two large and powerful fangs on each side 

 of the upper jaw ; head covered with rhomboidal, hexagonal, and polygonal 

 scales which are carinated ; the scales are largest upon the occiput and 

 sides of the head posteriorly; nostrils large, two lines in diameter, present- 

 ing upward and slightly backward ; eyes rather small, latero-superior, on 

 a line with the nostrils, and three lines posterior to them, slightly project- 

 ing, looking outward and a little upward ; palatine and infra maxillary 

 teeth recurved, sharp, pointed and strongly developed ; tongue long, bifid 



* Misprinted Arastes in the Proceedings, vol. ii. p. 250. 



42 



