ft bAtilA BLAffCA. 



almost to tumble off one's horse ; for in soft soil the animal burrowed 

 so quickly, that its hinder quarters would almost disappear before one 

 could alight. It seems almost a pity to kill such nice little animals, for 

 as a Gaucho said, while sharpening his knife on the back of one, " Son 

 tan mansos " (they are so quiet). 



Of reptiles there are many kinds : one snake (a Trigonocephalus, or 

 Cophias), 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 

 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 any- 

 thing 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 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 crau-ls 

 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, carried 

 it to a pool of water ; not only was the little animal unable to swim, 

 but I think without help it would soon have been drowned. 



Of lizards there were many kinds, but only one (Proctotretus 

 *) r-warkablf <r>w & teWts I* lives on the bare sand 



