connection it ought not to be overlooked that these fishes are not pelagic, like the Scomberoids, but rather archipelagic, if I may use this word to designate fishes dwelling among low islands. If we discard the long-prevailing idea of a close relationship between the Characines and Salmonides, based solely upon the presence of an adipose fin, we may at once perceive how manifold are the affinities between the Characines on one hand, and on the other the Scopelines and Clupeoids, all of which are essentially marine. These relations may be traced to the details of the genera; Gasteropelecus, from the family of Characines, is the pendant of Pristigaster among the Clupeoids, as Chalcinus recalls Pellona. In the same way may Stomias and Chauliodus be compared to Cynodon and the like; or Sudis and Osteoglossum to Megalops, and Erythrinus to Ophicephalus, &c., &c. The Goniodonts may at first sight hardly seem to have any kindred among marine fishes; but if we take into account the affinity which unquestionably links the genus Loricaria and its allies with Pegasus, and further remember that to this day all the ichthyologists, with the sole exception of C. Duméril, have united Pegasus in one order with the Pipe-fishes, it will no longer be doubted that the Goniodonts have at least a remarkable analogy with the Lophobranches, if they should not be considered as bearing a close structural relation to them. But this relation truly exists. The extraordinary mode of rearing their young, which characterizes the various representatives of the old genus Syngnathus, is only matched by the equally curious incubation of the eggs in Loricaria. And as to the other families represented in the basin of the Amazons, such as the Skates, the Sharks, the Tetraodonts, the Flat-fishes (Pleuronectides), the Bill-fishes (Scomberesoces), the Anchovis, Herrings, and other forms of the family of Clupeoids, the Murænoids, the genuine Sciænoids, the Gobioids, &c., &c., they are chiefly known as marine types; while the Cyprinodonts occur elsewhere both in salt and fresh water. The Gymnotines are thus far only known as fresh-water fishes, nor do I see any ground for comparing them to any marine type. They cannot be compared to the Murænoids, with which they have thus far been associated. The only real affinity I can trace in them is with the Mormyri of the Nile and Senegal, and with the Notopteri of the Sunda Islands. Eel-shaped fishes are by no means all related to one another, and their elongated form, with a variety of patterns, is no indication of their relationship. It may, nevertheless, be inferred from what precedes, that the fishes of the Amazons have, as a whole, a marine character peculiarly their own, and not at all to be met with among the inhabitants of the other great rivers of the world.