CURIOUS SNAKE loi 



observed a fact, which appears to me very curious and instruc- 

 tive, as showing how every cliaracter, 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 Trigo- 

 nocephalus has, therefore, in some respects the structure 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 terminated 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 Nto each other, somewhat proportional to those of the 

 human face ; and thus we obtain 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 vermilion, 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 Diabolicus, 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 reptiles possess great powers of cutaneous 

 absorption. At Maldonado, I found one in a situation nearly 

 as dry as at Bahia Blanca, and thinking to give it a great treat, 



