eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 159 



not reaching ventrals; distance from snout to dorsal 3.3-3.4 in the length, the spine 

 evident in the young, less than twice the length of the eye, becoming soft with age; 

 adipose dorsal long and low, connected with a forward extension of the caudal, 

 3.5 in the length; origin of ventrals near vertical from middle of dorsal or farther 

 back. 



Ashy to steel-blue above; fins hyaline. 



Myoglanis 15 gen. nov. 

 Myoglanis Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 384. 



Type, Myoglanis potaroensis sp. nov. 



First ray of dorsal soft; pectoral spine very strong; skull entirely covered above 

 by a thick layer of muscle; ventrals under posterior half of dorsal; caudal forked, 

 the lower lobe longest ; adipose long and low, continued to the caudal, there being 

 no caudal fulcra; a frontal fontanel, scarcely extending beyond the minute eyes; 

 skull behind the fontanel narrow, with a median ridge; occipital crest narrow and 

 short; eyes very smaU, directed slightly sidewise, mostly upward, no free orbital 

 margin; the two premaxillary patches of teeth forming a crescent; anal long. 



It is probable that the Acentronichthys collettii of Steindachner belongs to this 

 genus. 



36. Myoglanis potaroensis sp. nov. (Plate XIV, fig. 1.) 



Myoglanis potaroensis Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 



1910, 381 (name only). 



Type, about 58 mm. Creek at Tukeit. (Carnegie Museum Catalog of Fishes 

 No. 1664.) 



Cotypes, sixteen specimens, the largest 60 mm. Tukeit. (C. M. Cat. No. 

 1665a-d; I. U. Cat, No. 12048.) 



Cotypes, three specimens, 99-113 mm. Potaro Landing. (C. M. Cat. 

 No. 1666a; I. U. Cat, No. 12049.) 



Cotypes, three specimens, 35-40 mm. Waratuk. (C. M. Cat, No. 1667a; 

 I. U. Cat. No. 12050.) 



Cotype, one specimen, 33 mm. Erukin. (C. M. Cat. No. 1668a.) 



Cotypes, eight specimens, 32-80 mm. Amatuk. (C. M. Cat. No. 1669a-6; 

 I. U. Cat. No. 12051.) 



Head 4-4.3; depth 5.3-8; D. 6 to 8; A. 16-21; width of head equals its length 

 without snout; depth of head 2 in its length; eye 14 in head, 3.5 in snout, 5 in space 

 between the eyes. 



i6 m5s, muscle, TXdm, cat-fish. 



