22 CROTALUS OREGONUS. 



The nostrils are large and placed near the snout, but open laterally and a little 

 upwards.* 



The margin of the upper jaw is covered with fifteen labial plates, those near 

 the snout are quadrilateral, and those near the angle of the mouth are more 

 elono-ated. The neck is much contracted, and covered with small carinated 

 scales, of less size than those on the vertex, which are smooth. 



The body is elongated, but thick, and covered above with carinated, hexagonal 

 scales, and with large plates below. The tail is very short, and terminates in 

 several larae I'attles. 



"&^ 



Colour. The head above is ash colour, paler in front, darker behind, with a 

 transverse white line between the orbits; this line is slightly arched forwards, and 

 terminates on each side in the superior orbital plate, passing through its centre; 

 two other white lines are seen to begin, one above, and the other below the 

 nostrils; these lines unite behind the angle of the mouth; the margin of the upper 

 jaw below these lines is dusky. 



The body and tail are ash colour above, darker than the head, and marked 

 with two interrupted, zigzag, white lines, beginning about three inches from the 

 head and terminating at the tail; the lines of the opposite sides frequently run into 

 each other, and thus mark out a scries of dusky spots, margined with white; 

 these spots vary much, some are trapezoid, while others are rhomboidal, and 

 others again nearly triangular; on the neck and tail, where the hues do not exist, 

 there are only a few rounded, dusky spots, bordered with white. The plates of 

 the abdomen and tail are very dusky, with the posterior margin of each white. 



* Of the size of the eye and colour of the iris and pupil, and exact colour of the skin, I 

 can say nothing, as the animal above described had been for a long time preserved in 

 alcohol. 



