SOUTH AMERICAN NEMATOGNATHI. 331 



Trichomycterus gracilis Cuv. & Val. 1. c. 497 (Rio Azangaro near 



Guasacona; Rio Guatanai near Cuzco; Rio Pontezualo near 



Coroico; Lake Compucila near Cuzco); Cope, Proc. Am. Philos. 



Soc. xvii, 681,. 1877 (Tinta). 

 Trichomycterus barbatula Cuv. & Val. 1. c. 498 (Guasacoua; Rio 



Pontezualo near Coroico). 

 Trichomycterus pentlandi Castelnau, Anim. Nouv. Am. Slid, 49, pi. 



xxiv, fig. 1, 1855 (Lake communicating with the Ucayale). 

 Trichomycterus pictus Casteluau, Anim. Nouv. Am. Slid, 59, pi. 



xxiv, fig. 2, 1855 (Lake Titicaca). 

 Trichomycterus dispar Giinther, Cat. Fish. Brit. Mus. v, 273, 1864 



(in part); (Lake Titicaca; Rio de Pontezualo; Andes de la Paz; 



Guasacona Rio de Azangaro); Garman, Bull. Mus. Comp. ZooL 



iii, 275, 1875 (Lake Titicaca). 

 Habitat: Lake Titicaca; Ucayale and its tributaries. 



This species is readily distinguished from dispar and 

 punctulatus by the anterior position of the dorsal, the 

 rounded caudal and the abrupt change from short acces- 

 sory rays to the long caudal rays. The last character 

 was moderately figured by Castelnau. It differs greatly 

 in color and proportions at different ages. Cuv. & Val. 

 described individuals 7 inches long as rivulatus; 4J inches 

 long as incm; 3 inches long as gracilis; 2| inches long as 

 barbatula; while Castelnau represents the full grown in 

 his pentlandi the dorsal, however, has been misplaced. 



We have examined 120 specimens of this species, 

 mostly from Lake Titicaca. While the color markings 

 sometimes approach those of dispar and punctulatus, it 

 does not intergrade with them in the characters men- 

 tioned above. 



Most of the specimens mentioned by Dr. Giinther un- 

 der dispar are evidently rivulatus. The specimen from 

 the River Remac may be the punctulatus of Cuv. & Val. 



This species is very variable; it is only in the fully 

 grown, or specimens of about .35 m. long, that any con- 

 stancy seems to exist. 



In general form it resembles the North American. 

 Amiurus catus. 



