IN December of last year M. Vaillant communicated to the French Academy of Sciences a notice of a remarkable deep sea fish, to which he gave the name Eurypharynx pelecanoides. He was in great doubt as to the relations of this form, but concluded that “of all fishes it is to Malacosteus niger,” placed in the family Scopelidae by zoologists, that he was most inclined to approximate the new type. Five specimens of a nearly related form, to which Mr. J. A. Ryder and myself have given the name Gastrostomus bairdii, were obtained by the United States Fish Commission steamer Albatross, in the summer and autumn of the present year. The largest of these specimens is nearly two feet long, and an anatomical investigation reveals some very remarkable peculiarities of structure, which have caused Mr. Ryder and myself to differentiate the two forms, Gastrostomus and Eurypharnyx, in a distinct order of fishes to which we have given the name Lyomeri.