OPHIDIA. 



and more triangular; the space between the supraciliaries narrow, and 

 occupied by large angular scales, instead of small tuberculous ones. 

 In C. atrox, the row bordering the supraciliaries is much larger than 

 the rest, and the scales on the top of the head generally more angu- 

 lar. In C. lucifer, the line on the side of the head, instead of going 

 directly from the posterior end of the supraciliary to the commissures, 

 passes backwards nearly parallel to the mouth, crossing along the 

 fourth row of supralabial plates. The second line in front of the eye 

 is much wider below in C. lucifer, and the face generally shows more 

 of white, while the dark portions are much darker. 



Loc. This species inhabits the western coast of the United States; 

 specimens having been collected both in California and Oregon. 



Plate XV, fig. 1, represents Crotalus lucifer, size of life. 



Fig. 2, is a side view of the head. 



Fig. 3, an upper view ; and, 



Fig. 4, an under view of the same region. 



Fig. 5, is a front view of the head. 



Fig. 6, exhibits the dorsal scales. 



