160 MEMOIRS OF THE CARNEGIE MUSEUM 



Compressed behind, depth from occiput to middle of anal nearly equal; head 

 not greatly depressed, rounded above; occipital process short, its tip a little nearer 

 to the dorsal than to the line between the posterior margins of the eye: anterior 

 nostril very close to the lip; lips very thin, smooth; angle of snout below the eye; 

 maxillary barbel reaching tip of pectoral in the adult, somewhat farther in the 

 young; inner mental barbel in advance of the line joining the outer. 



Distance from dorsal to snout 2.6 in the length; tip of dorsal about reaching 

 adipose, which is about 3 in the length; caudal frequently divided to the base, 

 the lower lobe the longer; pectoral spine strong, not quite half the length of the 

 head, with recurved spines on both margins; anal long, the tips of some of the 

 rays reaching caudal, its base 3.5-4 in the length. 



Purplish brown, lighter below, the rayed fins lighter. No distinct markings. 



Chasmocranus 16 gen. nov. 

 Chasmocephalus Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 



384 (name only, preoccupied). 



Type, Chasmocranus longior sp. nov. 



First rays of pectoral and dorsal soft; origin of ventrals under origin of dorsal 

 or but slightly behind it, far in advance of the middle; caudal forked; top of skull 

 covered with skin only; fontanel narrow, extending to the base of the occipital 

 interrupted over the eyes and again some distance behind the eyes; occipital crest 

 short and narrow; eyes superior, without a free orbital margin; adipose fin low, 

 not connected with the caudal; premaxillary patch of teeth subrhomboidal, its 

 outer posterior angle extended backward; anal short. 



Closely allied to Heptapterus and Acentronichlhys. 



Key to the Species of Chasmocranus. 



a. Adipose fin 3.5-4.5 in the length longior. 



aa. Adipose fin about 6 in the length brevior. 



37. Chasmocranus longior sp. nov. (Plate XIV, fig. 2.) 



Chasmocephalus longior Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 



1910, 384 (name only). 



Type, 110 mm. Amatuk. (Carnegie Museum Catalog of Fishes No. 1655.) 



Cotypes, twelve specimens, 40-93 mm. Amatuk. (C. M. Cat. No. 1656a-c; 

 I. U. Cat. No. 12043.) 



Cotypes, three specimens, 95-129 mm. Maripicru ? (C. M. Cat. No. 1657a; 

 I. U. Cat. No. 12044.) 



16 xc£siua, a gaping, xpivov, head. 



