1833.] A HIDEOUS SNAKE. 105 



cephaltis, or Cophtas), from the size of the poison channel in 

 its fangs, must be very deadly. Cuvier, in opposition to some 

 other naturalists, makes this a sub-genus of the rattlesnake, 

 and intermediate between it and the viper. In confirmation 

 of this opinion, I observed a fact, which appears to me very 

 curious and instructive, as showing how every character, 

 even though it may be in some degree independent of 

 structure, has a tendency to vary by slow degrees. The 

 extremity of the tail of this snake is terminated by a point, 

 which is very slightly enlarged ; and as the animal glides 

 along, it constantly vibrates the last inch ; and this part 

 striking against the dry grass and brushwood, produces 

 a rattling noise, which can be distinctly heard at the distance 

 of six feet. As often as the animal was irritated or surprised, 

 its tail was shaken ; and the vibrations were extremely 

 rapid. Even as long as the body retained its irritability, a 

 tendency to this habitual movement was evident. This 

 Trigonocephalus has, therefore, in some respects, the struc- 

 ture of a viper, with the habits of a rattlesnake ; the 

 noise, however, being produced by a simpler device. The 

 expression of this snake's face was hideous and fierce ; the 

 pupil consisted of a vertical slit in a mottled and coppery 

 iris ; the jaws were broad at the base, and the nose termin- 

 ated in a triangular projection. I do not think I ever saw 

 anything more ugly, excepting, perhaps, some of the 

 vampire bats. I imagine this repulsive aspect originates 

 from the features being placed in positions, with respect to 

 each other, somewhat proportional to those of the human 

 face ; and thus we obtam a scale of hideousness. 



Amongst the batrachian reptiles, I found only one little 

 toad {Phryniscus nigricans)^ which was most singular from 

 its colour. If we imagine, first, that it had been steeped in 

 the blackest ink, and then, when dry, allowed to crawl over 

 a board, freshly painted with the brightest vermiHon, so as to 

 colour the soles of its feet and parts of its stomach, a good 

 Idea of its appearance will be gained. If it had been an 

 unnamed species, surely it ought to have been called 

 Diaholicus, for it is a fit toad to preach in the ear of Eve. 

 Instead of being nocturnal in its habits, as other toads are, 

 and living in damp obscure recesses, it crawls during the 

 heat of the day about the dry sand-hillocks and arid plains, 

 where not a single drop of water can be found. It must 

 necessarily depend on the dew for its moisture ; and this 

 probably is absorbed by the skin, for it is known that these 



