SOUTH AMERICAN NEMATOGNATHI. 463 



450, Dianema longibarbis, 



DianemalonyibarbisCope, l.c, 276, pi. vii, fig. 1-1& (Ambyiacu River). 



Head depressed, abruptly narrowed in front of the na- 

 res; maxillary barbels not reaching the opercular mar- 

 gin. Pectoral spine serrate within, dorsal spine acute, 

 not serrate. Eye 3J in the head; 2|- in the interorbital. 



Yellowish-brown, fins unspotted. 



Head 3; depth 3|; D.I, 7; A. 7; V. 7; P. I, 6; Lat. 

 pi. If; azygous plates 4. (Cope.) 



C. BROCHIS. 



Brochis Cope, Proc. Acad. Nat. Sci. Phila. 1871, 277 

 (cceruleus). 



Chcenothorax Cope, Proc. Am. Philos. Soc. 1878, 679 

 (bicarinatus). 



Type: Brochis cceruleus Cope. 



Habitat: Maraflon and tributaries. 



This genus differs from Cory dor as in the number of 

 dorsal rays. The degree of development of the coracoid 

 process in this case cannot be regarded of generic 

 value. The coracoid processes in all the species of this 

 group are exposed; in some (Brochis) they cover the en- 

 tire breast and belly, while in others (Chcenothorax) they 

 cover them only partially. This character varies with 

 the sex in some species of Corydoras, and varies still 

 more in Hoplosternum tlioracatum. 



ANALYSIS OF THE SPECIES OF BROCHIS. 



a. A series of plates between the ventrals and anal, another along the 

 sides of the dorsal. Cheeks and snout entirely mailed. Two rictal 

 barbels. D. I, 11. (Castelnau.) (Sub gen. nov. ?) taiosh 451. 



aa. Lower lateral plates meeting along, the median line of the ventral sur- 

 face. 



b. Two rictal barbels; coracoid processes extending to the ventrals, di- 

 verging behind, leaving a naked area between them. D. I, 11. 



(CHJENOTHORAX.) 



c. Eye more than 4 in the head, 2 in the snout, 2 in the interorbital. 

 Two azygous bones between the occipital crest and the dorsal 



