110. TRICHOMYCTERUS. 273 



skin. Operculum and interoperculum armed with a band of small 

 osseous prickles. Gill-openings rather wide, nearly continuous across 

 the throat. Ventrals five-rayed. 



South America; extending from the shores of the Pacific and 

 Atlantic into the Andes, to an elevation of 15,000 feet. 



1. Trichomycterus dispar. 



Pygidium dispar, Tschudi, Faun. Per. Ickthyol. p. 22. taf. 3 ; Gunth. 



Proc. Zool. Soc. 1859, p. 90. 

 Trichomj'cterus punctulatus, Cuv. fy Val. xviii. p. 488. pi. 552 (adult 



female). 



gracilis, Cuv. fy Val. xviii. p. 497 (young). 



barbatula, Cuv. fy Val. xvin. p. 498. 



pictus, Casteln. Anim. nouv. Amir. Sud, Poiss. p. 50. pi. 24. fig. 2 



(bad). 



B. 8. D. 10-11. A. 7-8. P. 9. V. 5. Vert. 22/15. 



The length of the head is nearly equal to the height of the body, 

 and one-sixth or one-seventh of the total. The origin of the dorsal 

 fin is in the middle of the distance between the occiput and the end 

 of the caudal fin. Mature specimens have the upper ray of the pec- 

 toral prolonged into a short filament. Males uniform brownish grey 

 above, whitish below ; females with numerous small dark-brown 

 spots on the back. 



Alpine rivers of Peru and Guayaquil. 



a. Male, 9 inches long. Western Ecuador. From Mr. Fraser's Col- 



lection. 



b. Female, 5^ inches long. River Rimac, Peru. Presented by Pro- 



fessor W. Nation. 



c. Adult. From Mr. Pentland's Collection. 



d-f, g, h. Young. Lake Titicaca. From Mr. Pentland's Collection 



(T. barbatula). 

 i-h. Young. Rio de Pontezualo. From Mr. Pentland's Collection. 

 V-n. Young. Andes de la Paz. From Mr. Pentland's Collection 



(2\ barbatula). 

 o-p,q-t. Young. Guasacona. From Mr. Pentland's Collection (T. 



gracilis). 

 u. Many young specimens. Rio de Azangaro. From Mr. Pentland's 



Collection (T. gracilis), 

 v, w, x-z. Young. From Mr. Pentland's Collection. 

 a. Young. 



2. Trichomycterus maculatus. 



Trichomycterus maculatus, Cuv. 8? Val. xviii. p. 493. 

 PThrichomycterus macraei, Girard, in V. S. Naval Astronom. Exped. 

 Zool. p. 245. 



D. 15. A. 9. P. 9. V. 5. 



Shorter than T. areolatus ; dorsal fin low and long ; pectoral without 

 prolonged ray. Back and sides yellowish, with greyish spots. ( Val.) 

 Santiago (Chile). 



