It will be observed that the word _Trigonocephalus_ is used as a generic name by some naturalists, and as a specific by others; and it may with reason be applied to most of the American thanatophidia which are not _elapidæ_. It therefore, at least, enables us to ascertain that the snake of doubtful identity has this viperine characteristic of the angular head; and as there is only one very small true viper at present known in the New World, we may further decide that not being an _Elaps_, our puzzler is a _Bothrops_ with the _doubles narines_, and therefore equally meriting either of the descriptives _atropos_, _atrox_, _furia_, _megæra_, _clotho_, _cophias_, and other such fearful appellatives freely used to designate the deadly qualities of the worst class of serpents. In reply to a communication of mine to _Land and Water_, of 2d October 1880, Dr. Stradling[126] entered more fully into this question of vernaculars, and what he says of Brazil we find to be the case everywhere:— ‘Whatever meaning the colloquial titles have is generally grounded on some popular error.’ This we saw in the case of _Xenodon_ and _Heterodon_, both called all sorts of bad names on account of their supposed fangs. ‘In Brazil, _Jeboia_ and _Cascavel_ are the universal names for the boa and rattlesnake; every snake with red in its markings is a coral snake (“corral,” from the Spanish word for a ring), every one found in or near the water would be a _Cobra de agua_, and every other is a Jarraracca or a Curucucu. ‘I believe every country has a pet bugbear among serpents. “Fer-de-lance” is the cry in St. Lucia when a snake rustles away in the bush or inflicts a bite unseen, “Bushmaster” in Demerara, “Toboba” in Nicaragua, “Vaia” in Mexico, “Vivera de la cruz” in the River Plate. Over and over again have I had snakes of widely different species sent to me, each guaranteed to be a genuine Jarraracca, until I began to doubt whether the Jarraracca had any existence at all. I believe that the one I sent to the Zoological Gardens the other day is the real thing—_Craspedocephalus Brasiliensis_—at last’ (the _Xenodon_ after all!) ‘and I think I have sifted the Curucucu down by elimination till I can fix the term on _Trigonocephalus atrox_. * * * * *