29 



CROTALOPHORUS TERGEMINUS.— %. 



Piatt V. 



Characters. Head large, triangular, rounded in front, covered anteriorly and 

 on the vertex with plates, and posteriorly with scales; a deep pit betAveen the eye 

 and nostril; upper jaw with poisonous fangs; body above cinereous, with a triple 

 series of dark brown spots; beneath a double series of dusky spots. — PI. 150. 

 Caud. PL 19. Bifid PI. 6. 



Synonymes. Crotalus tergeminus, Say, Long's Exped. Rock. Mount., vol. i. p. 499. 

 Crotalus tergeminus, Harlan, Med. and Phys. Res., p. 135. 



Description. The head is large, triangular, truncated in front, and covered 

 above with plates to behind the eyes. The vertical plate is large, pentagonal, 

 broad before, and pointed behind; the superior orbital are oblong, of equal 

 length with the vertical, but narrower, and project outwardly over the eye; the 

 occipital plates are rather large and irregularly rhomboidal; behind these the 

 head is covered with small scales; the frontal plates are broad, sub-pentagonal, 

 and rounded outwards; the anterior frontal are trigonal, with their bases directed 

 outward and forward; the nasal are quadrilateral and nearly of the same size; 

 the one is concave behind and the other before, to accommodate the nostrils. 

 There are two posterior orbital plates, and two inferior, of which the posterior 

 is long and narrow; there are two anterior orbital, the inferior making part of 

 the pit. The nostrils are lateral and near the snout. The upper jaw is covered 

 with twelve labial plates on each side. 



Colour. The ground colour of the Avhole animal above and at the sides is 



