250 PROCEEDINGS OF THE ACADEMY OF ON THE FISHES OF THE AMBYIACU EIVER. BY EDWARD D. COPE. The collection on which the present examination is based was made by our correspondent at Pebas, John Hauxwell. It em-braces fishes of the small streams tributary to the Ambyiacu, as well as those of the river itself. The Ambyiacu is an inconsid-erable river, which empties into the Amazon near to Pebas, in Eastern Equador, some distance east of the Napo. The results of the examination will be mentioned at the close of the list. As was to have been supposed, it consists almost exclusively of representatives of the three great families which abound in the neotropical region; the Ghromididae, representing Physoclystous fishes, and the Gharacinidse and Siluridae, repre-senting the Physostomi. The number of new species, forty-five in a total of seventy-four, constitutes a considerable addition to ichthyology, especially as the number of new generic forms is also rather large. I add a list of the species obtained by my friend Robert Per-kins, of Wilmington, Delaware, on a trip between the mouth of the Rio Negro and the Peruvian Amazon or Ucayale River. There are several interesting novelties in this collection, but their spe-cial localities are, unfortunately, not preserved. The specimens generally were large, and in fine condition. CHROMIDIDiE. PTEROPHYLLITM SCALARE, C. V. Heckel, Ann. Wien. Mms., 1840, 334. Giiuther, Catal. B. M. v. 316. Abundant in the Ambj'iacu. GEOPHAGTJS AMOENTJS, Cope, sp. nov. Allied to G. tseniatus {Mesops, Giinth.). Scales in three series on the cheek; on the body, 2-25-8. Fin radii D. xv. 7, A. iii. 6. Twelfth dorsal spine less than half the length of the head ; spines subequal, slightly shortening anteriorly. Prolonged soft raj^s of dorsal and anal extending beyond the caudal. Pectoral to, ven-tral beyond, base of anal. Length of head less than depth of [January 16,
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