166 OSTAEIOPHTSI. 



lateral line and base of ventral. Caudal peduncle nearly twice as long as deep. Brownish ; J'oung with 

 a dark lateral band. 



Ilah. Tributaries of the Rio Grande in Northern Mexico : 



Santa Rosalia in Chihuahua S; Coahuilai; Montemorelos in Nuevo Leon ^ 



{MccTc). 



Here described from two specimens, 60 and 85 mm. in total length. 



Fam. 4. CHARACINID2E. 



The Characinid^ comprise about 500 species from the fresh-waters of Mexico and 

 South America and 100 from Africa. The family is in many ways the most generalized 

 of the Ostariophysi, but is closely related to the Cyprinidae. In the Mexican and 

 Central-American species the body is scaly, the maxillary enters the gape of the mouth, 

 the branchiostegals number 3 to 5 and the gill-membranes are free from the isthmus. 

 An adipose dorsal tin is often present and the jaws are usually toothed. 



Si/nojjsis of the Mexican and Ceittral-Anierican Genera. 



I. Teeth well developed in both jaws. 



A. No adipose fin ; anal fin short, of 10-12 raj's ; body rather elon- 



gate ; mouth large J teeth conical 1. IIoplias. 



B. An adipose fin. 



1. Anal fin short, of 10-12 rays ; body rather elongate. 



Mouth moderate; teeth in jaws compressed, cuspidate ; palate toothless ; 



dorsal tin in the middle of the length of the fish 2. Piabucina. 



Mouth large, the snout produced, the jaws with small conical teeth in a 



single series ; palate toothed ; dorsal fin posterior in position ... 3. Luciocharax. 



2. Anal tin rather long, of 20 to 40 rays; teeth compressed, cuspidate. 

 a. Teeth of the outer series in both jaws subequal, without canines. 



a. Body oblong or ovate; abdomen in front of the ventral tins rounded. 

 A pair of conical teeth behind the middle of the series in the lower jaw ; 



praemaxillary teeth in 3 or 4 series 4. Buycon. 



No pair of conical teeth in the lower jaw; praimaxillary teeth in 2 series . 5. Tetragonopterus. 

 No pair of conical teeth in the lower jaw ; ]ir;emaxillary teeth in a siiigle 



series G. Chirodon. 



,6. Body deep ; abdomen in front of ventral tins compressed to 



a sharp edge 7. G astropelecus. 



i. Some of the anterior teeth enlarged, canine-like ; siiout 



somewhat produced 8. Brasiochabax. 



3. Anal fin very long, of 45 to 55 rays ; teeth conical ..... 9. Kcehoides. 



II. Jaws toothless ; anal fin short 10. Cuhimatus. 



