Evermann and Kendall Fish from Central Ecuador. < 93 



The third genus contains but one species, Astroblepus grixalvii 

 Humholdt. 



The genus Arges was erected by Cuvier and Valenciennes* to 

 include those species having bifid teeth and a ' ' long, low adipose 

 fin . " It was distinguished from Brontes by the latter 's having no 

 adipose fin. The first included Arges sabalo and Arges cyclopum; 

 the second Brontes prenadilla which Valenciennes says is of 

 identical structure in every way with Arges cyclopum except that 

 it has no adipose fin. He further says regarding the latter : 



They have shown to me that the fish of M. Boussingault indicates the 

 place that should be assigned to Attrofdrpus. It is, if the term be allow 

 able, an apodal prennd'dla; and the Pimdodus cyclopum is very probably 

 of the same genus as the sabalo. 



Steindachner has re-examined the types of Arges sabalo and 

 one of the two type specimens of Brontes prenadilla. Regarding 

 the latter he says : t 



Valenciennes's assertion that an adipose fin before the caudal is lacking, 

 is erroneous, and the figure in 1'Histoire Naturelle in plate 444 is one of 

 the numerous errors in this work. 



He further states that Glinther's Arges brachycephalus is 

 identical with Arges prenadilla Cuvier & Valenciennes. 



These two positive assertions, of Valenciennes and Stein 

 dachner, respectively, become significant from an examination 

 of our specimens. When first received these examples revealed 

 no trace of an adipose fin excepting what was soon discovered 

 to be a short spine, sometimes naked but in most cases concealed 

 under the skin, evidenced only by a slight elevation, which was 

 at first regarded as a short adipose fin " ; but in alcohol 

 there gradually appeared on the back a low, thick, fleshy fold 

 which increased in resemblance to a thick adipose fin with their 

 continuance in the preservative, and, in the smaller individuals, 

 became thin and very much like an adipose fin in appearance. 



Regarding the adipose fin in Arges sabalo, Steindachner says 

 (1. c.,p. 18): 



A more or less puffed, rather deep fold of skin begins on the back 

 behind the dorsal, at a distance equal to the whole or rather more than 

 half the length of the base of the fin, and unites with the upper caudal 



* Hist. Nat. Poiss., XV. 

 fFlussfische Sudam., IV, 21. 



