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Show 868.] DK. A. GUNTHER ON NEW AMERICAN FISHES. 245 fins; the fourth corresponding to the vent, the fifth to the middle of the anal, the sixth from the adipose fin, and the seventh round the last caudal scales. Anterior part of the base of the dorsal and the ventrals deep black ; the other fins yellowish. Several examples, the largest 6 inches long, were obtained by Mr. Bartlett at Xeberos. All of them have one side of the gill-cavity infested with a parasitic crustacean. TETRAGONOPTERUS OVALIS. D. 11. A. 26. L. lat. 31. L. transv. 5±/6. The height of the body is one-half of the total length (without caudal) ; the length of the head is contained thrice and two-thirds in it. Upper profile rather more convex than lower, slightly concave on the nape. The diameter of the eye is more than the width of the interorbital space, less than the length of the snout, and one-third of that of the head. The maxillary extends somewhat beyond the vertical from the front margin of the orbit. Origin of the dorsal fin immediately behind the root of the ventral. Pectorals extending beyond the ventrals, ventrals to the vent. There are four longitudinal series of scales between the lateral line and ventral fin. Humeral spot indistinct; caudal spot diffuse, extending over the base of the fin. Remainder of the body uniformly coloured. A single example, 4 inches long, was obtained by Mr. Bartlett at Xeberos. APHYOCHARAX, g..n. This genus belongs to the Tetragonopterina, and is, technically, distinguished from Chirodon by the presence of maxillary teeth. Dorsal fin placed in the middle of the length of the body, behind the ventrals ; anal rather long. Body oblong, covered with scales of moderate size. Lateral line visible on a part of the scales only. Abdomen rounded before the ventrals. Cleft of the mouth narrow ; maxillary short; intermaxillary, maxillary, and mandibles with a single series of pointed teeth, those in the intermaxillary having a minute lobe on one or both sides ; all the others appear to be simply pointed. APHYOCHARAX PUSILLUS. D. 9. A. 18. V. 8. L lat. 36. L. transv. 12. The hei°*ht of the body equals the length of the head, and is two-ninths of the total (without caudal). The diameter of the eye is two-sevenths of the length of the head, more than that of the snout, and less than the width of the interorbital space ; maxillary extending somewhat beyond the vertical from the anterior margin of the orbit. Intermaxillary with about seven, mandible with nine teeth on each side ; maxillary teeth very small, occupying about one-third of the length of the bone. Jaws even in front, the mandible projecting when the mouth is open. Origin of the dorsal fin midway between the end of the snout and the root of the caudal, behind the |