SOUTH AMERICAN NEMATOGNATHI. 325 



Habitat: Andes from Central Chile to Colombia; 

 Callao Bay; Amazon to Cudajas; Southeastern Brazil; 

 Central Argentine Republic. 



The only claim for retention the name Trichomycterus 

 possesses is its distinctiveness from Thrichomycterus 

 ~H.umb.=Eremophilus Humboldt. Twenty-two years be- 

 fore any species of Trickomyderus Val. was known, the 

 name Tkrichomycterus was proposed by Humboldt as an 

 alternative for his Eremoptiilus, if future investigations 

 should prove Eremophilus to be objectionable. Upon 

 proposing the name Trichomycterus Valenciennes states: 

 " Nous prenons pour le nouveau genre le norn de Trich- 

 omycterus imagine par M. de Humboldt/' so the names 

 can hardly be considered distinct. Valenciennes after- 

 wards misquotes himself, spelling the name TnRYchomyc- 

 terus instead of Tmchomycterus. Girard also misquotes 

 Valenciennes, using Thrichomycterus instead of Trichomyc- 

 terus. 



The only available name for this genus seems to be 

 Pygidium, based on some fish found floating in a river 

 of Peru. 



DOUBTFUL SPECIES OF PYGIDIUM. 



As most of the young of the species of Pygidium are 

 very much alike in coloration, and usually entirely dif- 

 ferent from the adult, we are compelled to place here 

 most of the species based on young individuals, unless 

 they were collected together with large individuals. 



256.1. Pygidium fuscum Meyen, 1. c. (Peru); Wieg- 

 man, Wiegman's Arch. 1835, ii, 269 (copied). By put- 

 ting together the two descriptions quoted and the local- 

 ity, one may infer that this species belongs to the genus 

 Trichomycterus auct. 



256.2. Trichomycterus palleus Philippi, MB. Ak. Berl. 

 1866, 715 (Chile). Light reddish; fins colorless; head 

 6J in total. D. 9-10; A. 6. 



