28 CROTALUS ADAMA.\TEUS. 



The nostrils are large, lateral, and near the snout; the pit between the orbit 

 and nostrils is remarkably large. The eyes are large, the pupil elliptical, vertical 

 and dark; the iris Ught gray, with a tinge of yellow. 



The mouth is large, the upper jaw furnished with poisonous fangs, and covered 

 externally with twelve labial plates, all of which are quadrilateral, the largest in 

 front. The neck is remarkably small and contracted; the body elongated, very 

 thick, even to the tail; above it is covered with scales, approaching an hexagonal 

 form, and strongly carinated on the vertebral line, less so near the abdomen, which 

 is covered with very large plates. The tail is short and thick, with scales and 

 plates below, and sustains a greater or less number of rattles. 



Colour. The head is very dark brown above, with a light coloured hne 

 descending from near the snout to the angle of the mouth; above this is a broad 

 black vitta, reaching from the orbit of the eye nearly to the neck; and above this 

 again is a white line of the same extent and direction. The neck and body are 

 a dusky-brown, sometimes tinged with a dusky-green — indeed the whole colour 

 of this animal is singularly dingy — the body is marked with a series of regular 

 rhombs, of the darkest brown, lighter towards the middle; each rhomb is bordered 

 with a margin of dirty white; these gradually disappear towards the tail, and their 

 place is supplied by dusky bars, which in the end also disappear, so that the tail 

 is dusky near the rattles. 



Dimensions. Length of head, 2? inches; greatest breadth of head, 2^ inches; 

 circumference of the neck, 4 inches; length of body, 60 inches; length of tail, 2k 

 inches; length of rattles, 3" inches. In the individual here described, there were 

 172 abdominal plates, and 25 sub-caudal. 



Habits. The Crotalus adamanteus chooses for its abode damp and shady 

 places, keeping constantly near the water, from which circumstance it is com- 

 monly called the "Water-rattle," though there is no evidence of its taking to the 

 water in search of prey. 



