s 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, subsequently called by M. Bibron T. crepitans), 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 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
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 i