Cope. } 46 {May 4, 
Head one-sixth total length;* D. 7-8; A. 5-6; form 
slender ; spots few, large....... ara Sai tte ale easter flo aictotera tarot eke T. pardus. 
II. Dorsal fin partly over anal fin. 
a. Dorsal fin partly over ventrak. 
Head 4.5 to 5.5 in total length; D.9; A. 6; gray, uni- 
fomm-orplackrspeckledst.% oseeeistenen se shcs eeeeieee : T. dispar. 
aa. Dorsal fin behind base of ventrals. 
Head 5 times in total; D. 7; A. 5; closely marbled with 
dark brown above and below...» s+ «sss eceneec< Spies eite T. rivulatus. 
Head 6 times in total; D. 7; A. 6; straw-colored with a few 
TUMMSRSPICELES AUN chcte <-o re “crs arate oe rie a aikie: alavetemie teen acted hore are T. gracilis. 
Head 6.5 and 7 times in total; D.8; A. 6; coarse, brown, 
confluent blotches, finer above anteriorly; forming two 
series posteriorly with pale band between.... ..........::- T. poeyanus. 
The species, 7. maculatus, T. punctulatus and 7. areolatus C. & V., are 
characterized by a larger number of rays (11-15) in the dorsal fin, than 
that found in any of the preceding. 
38. TRICHOMYCTERUS DISPAR Tschudi; Giinther, Catal. Brit. Mus. V, p. 
278. 
All the specimens of this species as above defined come from the head- 
waters of the Amazon, as was found to be the case by Tschudi (see Fauna 
Peruana). They are Nos. 89 and 92-4 and 101 from Tinta on the Vilcan- 
ota, the source of the Ucayali, elevation 11,400 feet ; Nos. 57-60 and 113- 
121 from the Rio Urubamba at Urubamba, elevation 10,000 feet. The very 
young have an interrupted dark lead-colored lateral band, which with 
growth is resolved into spots, and disappears. None of the specimens 
present the numerous dorsal radiiascribed by Dr. Giinther to his 7. dispar, 
which is doubtless the 7. maculatus of Cuv. Val. 
39. TRICHOMYCTERUS RIVULATUS Cuyv. Val. Vol. XVIII, p. 495. 
This species, which is characterized by a smaller number of dorsal radii 
than the last, among other points, is represented by a large specimen 
(No. 143) from Lake Titicaca. Native name, Suche. 
40. TRICHOMYCTERUS GRACILIS Cuv. Val. XVIII, p. 497. 
The principal characters of this fish have been already pointed out. I 
add the following : 
The depth of the body is one-sixth the total length with caudal fin. 
The eye is a little nearer the line connecting the posterior borders of the 
opercula than that which is tangent to the end of the muzzle. Nasal bar- 
bel extending a little beyond the eye. Radii; D. 61; C. 4-11-38; A. 51; V. 
Jha ee eee )y 
The color is a greenish straw-color with very faint dots closely placed 
on the dorsal region ; lower surfaces unicolor ; spots more distinct on top 
of head. An indistinct dark band extends on each side of the dorsal region 
from the beard to behind the dorsal fin. 
*Tneluding caudal fin. 
