SOUTH AMERICAN NEMATOGNATHI. 349 



290. Arges longifilis. 



Arges longifilis Steindachuer, Flussfische Siidam. iv, 19, pi. v, fig. 



3-36, 1882 (Kio Htiambo). 

 Habitat: Rio Huanibo. 



291, Arges peruanus. 



Arges peruanus Steindachner, Ichthyol. Beitr. xiv, 51, pi. ix, figs. 3-6 

 (Amable Maria); id. Fhissfische Siidam. i, 23, 1879 (Amable Ma- 

 ria; Tambillo; Chota). 



Habitat: Andes of Peru. 



LXIX. CYCLOPIUM. 



Pimelodus Humboldt, Obs. Zool. i, 21, pi. 6, 18. (sp.) 



Arges Guv. & Val. xv, 340, 1840. (sp.) 



= Cydopium Swainson, Nat. Hist. Fish, ii, 305, 1839 

 (humboldtii= cyclopum) . 



Stygogenes Giinther, Cat. Fish. Brit. Mus. v, 223 

 (humboldtii). 



Type: Pimelodus cyclopum Humboldt. 



Adipose fin short, placed near the caudal, with a short 

 spine. Teeth small, those of the mandibles and the inner 

 ones of the intermaxillary broadened and notched at the 

 tip. Eyes small, placed on the upper surface of the head. 



If the species Pimelodus cyclopum is ever to be recog- 

 nized it must be referred to the genus Stygogenes Giinther 

 = Cyclopium Swainson. The poor description of P. cyclo- 

 pi.i in makes an absolute identification impossible. There 

 are, however, in the Museum of Comparative Zoology, 

 two specimens from Quito i. e. from the habitat of P. 

 cyclopum which fairly agree with the figure and de- 

 scription of P. cyclopum, leaving out of consideration 

 the spine in the adipose fin. They also agree with the 

 description of Stygogenes humdoldtii Gthr. with the ex- 

 ception of the number of fin rays. The two species may 

 be considered identical. Putnam (Am. Nat. 1871) 

 identifies with it also Arges brachycephalus , but a re-exam- 

 ination of the types of the two forms by Dr. Giinther 

 proves them to be distinct. 



