84 Field Columbian Museum — Zoology, Vol. V. 



maxillaries protractile; teeth various, often incisor-like, often wanting; 

 branchiostegals usually 3 ; gill membranes united to the isthmus or 

 not; no pseudobranchiae ; gills 4, a slit behind the fourth; lower 

 pharyngeals more or less curved, armed with small, sometimes villi- 

 form, teeth; adipose fin present (occasionally wanting) ; air bladder 

 transversely divided into two portions; anterior vertebrae coalesced 

 and modified. 



A large family of fishes inhabiting the fresh waters of South 

 America and Africa. A few species inhabit the streams of southern 

 Mexico, ranging as far north as the United States. All of the mem- 

 bers of this family in Mexico are small, none reaching a length of 

 over six inches. 



KEY TO THE GENERA OF CHARACINID^E. 



a. Scales large, less than 50 in the lateral series; page 



anal fin short, with less than 35 rays, 

 b. Anterior teeth strong, incisor-like; premax- 

 illary teeth in a double series, those on man- 

 dible in a single series; less than 40 scales 

 in the lateral series; lateral line complete . . Tetragonoptcrus 84 

 bb. Anterior teeth weaker, more or less conical 

 and with lateral cusps; more than 40 scales 

 in the lateral series; lateral line incomplete. Hanigrammus 87 

 aa. Scales small, more than 60 in the lateral series; 



anal fin long, with more than 40 rays Raeboides 88 



Subfamily Tetragonopterinee. » 



35. Tetragonopterus Cuvier. 



Tetragonoptcrus Cuvier, Regne Animal, Ed. 1, Vol. 11, 166, 1817. 

 (Type, Tetragonopterus argenteus Cuvier.) 



Astyanax Baird & Girard, Proc. Acad. Nat. Sci. Phila., 1854, 26. 

 (Type, Astyanax argcntatus Baird & Girard.) 



Body oblong or elevated, compressed, covered with moderate 

 scales; belly rounded; mouth rather small; anterior teeth strong, 

 incisor-like; lateral teeth small; premaxillary and mandibular teeth 

 about equal in size, with a compressed, notched crown, the former 

 in a double, the latter in a single series; nostrils of each side close 

 together, separated by a valve only; lower pharyngeals very slender, 

 curved, armed with a single series of slender, hooked teeth; gill 

 openings wide; gill membranes not connected, free from the isthmus; 

 origin of the dorsal fin about midway between tip of snout and base 

 of caudal. 



