116 CROTALUS OREGANUS. 



angle of the mouth are more elongated. 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 'diick, and covered above with carinated hexagonal 

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

 several large rattles. 



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 is 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 series 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 lines 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. 



Dimensions. Length of head, 9 lines; length of body, 12^ inches; length of 

 tail, with rattles. If inches; total length, 15 inches. The specimen here described 

 had 177 broad plates on the abdomen, and 22 under the tail, and 3 large rattles. 



Habits. Nothing is known of the habits of the Crotalus Oreganus. 



GEOGRApmcAL DISTRIBUTION. This animal was found in the country west of 

 the Rocky Mountains, on the banks of the Oregon or Columbia river. 



