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Show 1870.] DR. A. GUNTHER ON PROTOTROCTES. 151 single example which was obtained for the British Museum of fishes sent from Victoria to the International Exhibition in 1862 (Fish. v. p. 382). I then associated it with Haplochiton, a genus inhabiting cold fresh waters of Tierra del Fuego, of the Falkland Islands, and of the southern parts of the South American continent. The characters, as far as they could be observed, seemed to warrant the propriety of uniting the two genera into a family, Haplo-chitonidee; and for the new genus the name of Prototroctes (in allusion to its Salmonoid affinities) was proposed. A few days ago two perfect specimens of the latter genus, preserved in spirits, were submitted to m y examination*; and I am now enabled to complete the description of the generic characters, as well as to add a second species to the genus. These fishes have entirely the appearance of Coregonus. The body is covered with cycloid scales of moderate size ; the first dorsal short, immediately behind the middle of the length of the fish, and immediately behind the insertion of the ventral fins; adipose fin small, opposite to the end of the anal, which is not much longer than the dorsal. Caudal fin forked. The structure of the mouth is entirely different from that of Coregonus ; it is of moderate width, and cleft to below the eye ; the snout is pointed, with a mesial notch to receive the soft skinny end of the lower jaw ; the intermaxillary and maxillary are intimately attached to each other along their whole length, and the margin of the upper jaw is formed by the intermaxillary only. The upper jaw is provided with a series of minute teeth, slightly bent inwards, very similar to those of Mugil, not anchylosed to the bone, but imbedded in a cartilage with which the intermaxillary bone is covered. Lower jaw with a series of minute teeth, which are more distantly placed than those of the upper, and inserted in the bone itself: a layer of horny substance, such as is found in many Cyprinoids, intervenes between the upper and lower jaws, and is easily detached from the lower. Vomer and palatine bones with a single series of minute teeth ; tongue on each side with a series of small recurved teeth. Gills four. Pseudobranchiee none. Branchiostegals six, short, broad, as in Coregonus. Air-bladder large, simple. Stomach caecal, slightly more muscular in its cardiac and pyloric portions than in the middle. Pyloric appendages none. Intestinal tract of moderate length, one-half longer than the entire fish. Peritoneum of a deep black colour. Both our examples are unfortunately males, so that the condition of the ovaries and oviduct is still unknown : it seems that the testicle is developed on the left side only, where it forms a long, broad, and very thin lamina ; a vas deferens connects this lamina with another smaller one situated in the hindmost part of the abdominal cavity. Urogenital orifice with a very small and short tube. It is evident from this description that the union of Haplochiton and Prototroctes in one family is perfectly justified, although the pre- * They were in the first instance (Nov. 1869) sent by the Westland Naturalists' Society of N e w Zealand to Mr. Buckland, who eventually requested me to give an opinion about them. |