May 17, 1878.] 673 [Cope. 
Synopsis of the Fishes of the Peruvian Amazon, obtained by Professor Orton 
during his Expeditions of 1873 and 1877. 
By E. D. Corr. 
(Read before the American Philosophical Society, May 17th, 1878.) 
The present paper consists of a catalogue of one hundred anc twenty 
species of fishes which were obtained by the late Professor James Orton, 
from the head streams of the Amazon. The localities from which the 
specimens were derived, are the following : Cuzco, on the Urubamba near 
the head of the Ucayale ; Moyabamba and Balsa Puerto on or near the 
lower course of the Huallaga ; Nauta on the Marafion at the mouth of the 
Ucayale, and Pebas below the mouth of the Napo. The larger part of 
the collections of 1873 came from Nauta, while those of 1877 were partly 
obtained near Pebas. The specimens from the Urubamba are the only 
ones taken at a great elevation, that of 11,000 feet. A recapitulation will 
be given at the close of the Catalogue. The collections contain numer- 
ous species previously known, as well asa number of interesting novelties. 
HOLOSTOMI. 
SYMBRANCHIDA. 
1. SyMBRANCHUS MARMORATUS Bloch. 
Coll. 1873. 
NEMATOGNATHI. 
HyYpPoPHTHALMIDA. 
2. HyroPHTHALMUS EDENTATUS Spix. 
Coll. 1873. 
3. HyPpoOPHTHALMUS PERPOROSUS, sp. nov. 
Established on a rather large specimen in good preservation. Radii; D. 
J. 6; A. 67; V. I. 5. The dorsal fin is small, and is situated 35 mm. nearer 
the end of the muzzle than the base of the superior fulcra of the caudal 
fin ; it originates above the seventh ray of the anal fin. The extremities of 
the ventrals do not extend beyond those of the pectorals. The spine of the 
latter is very weak, although longer than that of the dorsal, and is one- 
third the length of the head. The head enters the length minus the caudal 
fin four and one-seventh times, and is just equal to the depth of the body 
at the anterior part of the anal fin. The eye is one-thirteenth the length of 
the head, and one-sixth the length of that part of the head anterior to it. 
The fissure continued from the canthus oris extends to below its center. 
One eye is a little more elevated than the other, the one having some in- 
ferior range, the other none. The maxillary barbels commence nearer to 
the angle of the mouth than to the base of the posterior mental barbels, and 
extend to a little beyond the base of the ventral fin. The mental barbels 
are on nearly a transverse line, and are broadly margined posteriorly ; they 
PROC. AMER. PHILOS. soc. xvi. 101. 4F. PRINTED JUNE 1878. 
