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CROTALOPHORUS TERGEMINUS.—Say. 
Plate V. 
Cuaracters. Head large, triangular, rounded in front, covered anteriorly and 
on the vertex with plates, and posteriorly with scales; a deep pit between 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 Pl. 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. 
Corour. The ground colour of the whole animal above and at the sides is 
