EIGENMANN: the freshwater fishes of BRITISH GUIANA 167 



Rhamdella Eigenmann and Eigenmann. 



Rhamdella EiG-ENMANTS! and Eigenmann, Proc. Cal. Acad. Sci., (2), I, 1888, 129 



(eriarcha) . 



Type, Rhamdella eriarcha Eigenmann and Eigenmann. 



This genus differs from Rhamdia in the presence of a long slit-like parietal 

 fontanel. Most of the species are found in southeastern Brazil. 



43. Rhamdella foina (Miiller and Troschel). 

 Pimelodus foina Mijller and Troschel, in Schomburgk, Reisen, III, 1848, 628 



(Takutu); Horae Ichth., Ill, 1849, 5 (Guiana). — Gijnther, Catalogue, V, 



1864, 130 (copied). 

 Rhamdia foina Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), I, 1888, 126 



(name); Occasional Papers Cal. Acad. Sci., I, 1890, 126; Proc. U. S. Nat. Mus., 



XIV, 1891, 28. — Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 



1910, 386. 



This species has been taken but once before; I have examined the type in 

 Berlin and five specimens, 141-201 mm. Warraputa Cataract. (C. M. Cat. No. 

 1587a-6; I. U. Cat. No. 12007.) 



Head 4; depth 5-6.5; D. I, 6; A. 10. 



Head much depressed, its depth equal to eye and postorbital part of head, its 

 width equal to the length behind the maxillary barbel; head evenly arched from 

 its lower margin to its lower margin, the eyes directed upward and outward, 4 in 

 the head, two-thirds of the interorbital ; occipital fontanel long and narrow; occip- 

 ital process very short, extending about one-fourth of the distance to the dorsal 

 spine. Premaxillary teeth fine, in a band of about equal width throughout. 

 Maxillary barbel extending slightly beyond tip of pectoral; post-mental a little 

 beyond their base. 



Dorsal spine two-fifths the length of the head; base of dorsal a little less than 

 its distance from the adipose, which is 3.5 in the length. Caudal forked, not cleft 

 to its base, the lower lobe rounded, the upper lobe pointed, .4 longer than the 

 lower, 3.5 in the length; depth of caudal peduncle about half its length. 



Uniform blue-black to mottled ashy; dorsal uniform or its base darker. 



Pimelodella Eigenmann and Eigenmann. 

 Pseudorhamdia Steindachner, " Susswasserfische Siidostlichen Brasilien," iii, 1876, 



46 {lateristriga) , not Pseudorhamdia Bleeker. 

 Pimelodella Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), I, 1888, 131 



(cristatus) . 



