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Show 1809.] DR. A. GUNTHER ON NEW FISHES FROM PERU. 423 The species of the Pig-family, as far as at present known, are infested by comparatively few parasites, which, when we bear in mind their uncleanly habits and mode of life, is rather singular. Our common Pig has but one parasite, the Heematopinus urius of Nitzsch, or H. suis of Burmeister and Denny. It is an interesting fact that this genus Gyropus seems peculiarly American in distribution : the G. hispidus of the Ai, G. gracilis and G. ovalis of Cavia cobaya, and G. longicollis of Dasyprocta agree with G. dicotylis in being from the western hemisphere. All the other species are of minute size, the Gyropus ovalis being T y , G. gracilis 7-V', G- longicollis \ of a French line, G. hispidus about the same size. This species, being one-seventh of an inch in length, may fairly be reckoned as a giant in the genus. 4. Descriptions of some Species of Fishes from the Peruvian Amazons. By Dr. A L B E R T G U N T H E R , F.R.S., F.Z.S., &c. Some collections of fishes sent by Mr. E. Bartlett from the Upper Amazons were noticed in Ann. & Mag. Nat. Hist. 1866, xviii. p. 30, and in Proc. Zool. Soc. 1868, p. 229. In this paper I intend to describe those species which were brought home by this traveller on his return to England, and which prove to be new. Unfortunately the specimens are not in so good a condition as those previously sent. The proportion of new forms is much less than we might have expected from those almost unexplored parts of the river Amazons, Mr. Bartlett's collections having added only twenty-three species to this fauna. I may mention that the last collection contained also Sorubim lima (Bl. Schn.), Rhytiodus microlepis (Kner), and Myletes asterias (Miill.). MEGALOBRYCON, g. n. This genus is closely allied to Bryconops, from which it is technically distinguished by the presence of a maxillary series of teeth. Dorsal fin placed in the middle of the length of the body, immediately behind the ventrals. Anal long. Abdomen rounded in front of, and somewhat compressed behind the ventrals. Cleft of the mouth of moderate width. Teeth notched, in a triple series in the intermaxillary, and in a single in the maxillary and mandible ; no other teeth behind the mandibulary teeth or on the palate. Nostrils close together. Gill-openings wide. Scales of moderate size, with the free portion striated. MEGALOBRYCON CEPHALUS. (Fig. 1, p. 424.) D. 11. A. 24-26. L. lat. ca. 70. The height of the body is one-third of the total length (without caudal), the length of the head one-fourth. Intermaxillary in a triple series, those of the outer series being smillest, about twice as large as those of the maxillary ; the front mandibulary teeth largest. |
