1878, ] 691 [Cope. 
82. TETRAGONOPTERUS HAUXWELLIANUS Cope, Proceed. Amer. Philos, 
Soc. 1870, p. 560. 
Coll. 1873. 
85. Te PRAGONOPTERUS CHALCEUS Agass. 
Coll. 1877, from the Marafion. 
84. TETRAGONOPTERUS ORTONII Gill. Proceed. Acad. Phila. 1870, p. 92. 
Coll, 1873. 
85. TETRAGONOPTERUS AGASSIZII Steindachner, Sitzungsber., K. K. Akad. 
Wiss. Wien, 1876 (July) 41, Pl. VIII, fig. 2. 
Two specimens from near Pebas resemble the species above named in all 
points excepting in the more elongate body, so that I suspect them to repre- 
sent a local race. There are 1.24 anal radii, and the longitudinal rows of 
scales are 5—1+3-4. The total length without caudal fin is M. .034; 
depth .013 ; length of head .0105. The caudal spot is very large, covering 
the basal half of the fin, while the humeral spot is obsolete. 
86. TETRAGONOPTERUS LONGIOR, sp. nov. 
One of the more elongate forms of the genus. Radii D. I. 10; A. I. 24. 
Longitudinal series of scales twelve. The greatest depth enters the length 
less the caudal fin 4.7 times, and the length of the head the same 4.2 times. 
The diameter of the orbit enters the length of the head 3.5 times, and the 
interorbital width 1.33 times. The maxillary bone is toothless, and rather 
wide, and extends little beyond the line of the anterior border of the orbit. 
The origin of the dorsal fin is behind the line of that of the ventrals, and is 
nearer the origin of the caudal fin than the end of the muzzle by the length 
of the latter. 
There is a broad silvery lateral stripe, on which is a strong black hume- 
ral spot. There is no distinct basal caudal spot. Total length .095. 
Coll. of 1874, from Moyabamba. 
87. TETRAGONOPTERUS, sp. indet. 
Coll. of 1873. 
88. TETRAGONOPTERUS, sp. indet. 
Coll. of 1873. 
89. TETRAGONOPTERUS DIAPHANUS, Sp. NOV. 
An elongate species distinguished by the small number of its anal rays. 
D. 1.9; A. I. 18; V. 7, originating a little anterior to line of dorsal, and 
not reaching anal: P. 15, not reaching ventrals. Dorsal fin nearly equi-dis- 
tant between end of muzzle and base of caudal fin. Anterior rays of dorsal 
and anal fins markedly longer than the posterior. Depth entering length 
less caudal fin three and one-seventh times ; length of head into the same, 
four and two-fifth times. Scales 4-35-3.5 ; lateral line complete. Maxillary 
bone toothless, extending near tothe line of the anterior border of the 
orbit. The latter enters the length of the head 2 and 3-4th times, equal- 
ing the interorbital space. 
Total length M. .052; of head .011; to line of ventral fin .020; to line of 
