Echoing my own perplexities, he asks, ‘_Is_ there such a snake as the _Jarraracca_? When I got three more living specimens of the same this last voyage in Pernambuco, I began to have my doubts, for I could not reconcile them with the description at all. One died, which fact I did not, by ill luck, discover till it was worthless; but I observed, as I thought, a well-developed fang. A few days later a good opportunity presented itself for picking up one of the survivors and examining its mouth; then to my surprise I found that the supposed fang was really a large curved tooth, situated quite out of the natural position of a fang, but symmetric with one on the opposite side. Then I looked at the other one, and finally let both bite me, which settled the matter. I set it down as _Xenodon_ (a harmless snake), and was gratified to find on reaching home that Dr. Günther had pronounced my specimen at the Gardens’ (the one brought the previous September) ‘_Xenodon rhabdocephalus_, the long-headed snake, on its death. But I don’t find any mention of this extraordinary isolated tooth anywhere, though I have a vague idea that Dr. Wucherer, who has perhaps been the most earnest student of the Brazilian Thanatophidia, spoke of it in a communication to the Society some years ago. The real “Jarraracca” is still veiled in mystery.’ I also was ‘gratified’ to find the Corresponding Member of the Zoological Society so generously justifying my doubts about the supposed _Jararaca_, both in his letter to me and in a paper to _Land and Water_, 2d April 1881. This was the first time I had ever heard of a _Xenodon_, a name which Dr. Günther was then so good as to explain meant ‘strange tooth;’ and he drew a little diagram of the jaw with five simple teeth curving back, and then a long, fang-like back tooth. Strange indeed! _Heterodon_ I knew possessed a large, fang-like tooth, which had caused it to be called ugly names. Now here is more heterodox dentition. Dr. Wucherer’s account of the _Xenodon_ was discovered in the _Zoological Society Proceedings_ for 1861. He also had been a C.M.Z.S.[112] in the same region, and his report of the curious _Xenodon rhabdocephalus_ is that it is very voracious, feeding chiefly on frogs, but will swallow his friend too, should the latter have hold of one on which he has set his heart. It flattens itself remarkably, and thus gets through a very narrow chink. It is a fresh-water snake, called _Cobra d’aqua_ in Brazil, also _Surucucu_ (from its evil reputation). But Dr. Wucherer says not a word of those fang-like teeth. Meanwhile Dr. Stradling had most kindly sent me the magnificent specimen of ‘_Curucucu_’ (_Lachesis mutus_), in spirits; and this, together with the investigation of certain other vernaculars, made the _Xenodon_ of only secondary interest in our correspondence until exactly six months afterwards, when, on landing, June 1881, he wrote that he was sending a _Heterodon_ and another _Xenodon_ to the Gardens.