20 CROTALUS ADAMANTEUS. 



its colour, on a superficial examination, appears similar; but, observed attentively, 

 there will be found enough, even in this, to distinguish the two animals. The 

 Crotalus horridus has a black band across the forehead, embracing the anterior 

 part of the superior orbital plates; behind this, and reaching through the centre 

 of these plates, is a white bar across the vertex. Another black band runs from 

 the eye to the angle of the mouth; two large bands, of similar colour, begin 

 behind the occiput, and run along the neck and back to the distance of about 

 one-fifth of the whole animal; these latter bands are of the breadth of two scales 

 and a half; two other narrower bands, and of the same length and colour, depart 

 from the temples; wliile the Crotalus adamanteus is dusky-brown, without any 

 black marks on the head, and has the rhomboidal spots, beginning at the back of 

 the occiput, and continuing along the whole extent of the animal to near the 

 extremity of the tail, which is banded. Besides the diflerence in colour between 

 these two animals, there is a difference in the plates about the head. In the 

 Crotalus horridus the nasal plates arc verj^ small; the frontals are triangular and 

 also very small, while the vertex between the orbits is covered with plates or 

 scales much larger than in the Crotalus adamanteus or Crotalus durissus. It is 

 highly probable that the figure of the Crotalus durissus of ShaAv represents our 

 animal, but the description refers certainly to the Crotalus durissus, and it is 

 mostly taken from Catesby. 



