eigenmann: fresh water fishes. 253 



A third one is recorded from south of Buenos Aires without a distinct 

 locality.' It is without scales and forms a distinct subfamily closely allied 

 to the Tetragonopteriiicc. 



The relation of the Patagonian forms to those of other regions is shown 

 by the following keys to the subfamilies of CharacidcB and to the genera 

 of Tetragonopterince. 



SUBFAMILIES OF CHARACID^.' 



a. Teeth none ; an adipose fin. 



/'. Gill-rakers none ; intestine very long. I. Curimatince, American. 



hb. Gill-rakers long, clupeiform ; fourth gill arch with raker-like organs behind. 



II. Anodina, American. 

 aa. Teeth minute, mostly depressible ; nares close together ; gape short, mouth usually small ; an 

 adipose fin. 

 c. Last gill-arch normal. 



d. Jaws well developed, the mandibles firm ; teeth more or less spatulate, more or less 

 firmly joined to the jaws ; dorsal variable. 

 e. Scales cycloid ; teeth serrate or spoon-shaped ; gill-membranes free from isthmus 

 and from each other; no predorsal spine. III. Hemiodontince, American. 



ee. Scales ctenoid. 



f. Gill-membranes free from the isthmus. IV. Neolebiince, African. 



ff. Gill-membranes joined to the isthmus. V. Distichodontince , African. 



dd. Jaws very weak, mandibles transverse ; teeth on the margins of fleshy lips, freely 



movable, spatulate ; mouth subterminal, broad ; dorsal short ; gill-membranes 



joined to isthmus ; a movable, procumbent, predorsal spine. 



VI. Prochilodina, American. 

 cc. Last gill -arch modified. 



' GYMNOCHARACINUS Steindachner. 



(Plate XXXIV, Figs. 3 and 3«.) 



Gyiiinocharacinus Steindachner, SB. Akad. Wiss. Wien, CXII, 20, 1903 (type bcrgii). 

 This genus differs from all other Characins in being naked. 



GvMNOCHARACiNus BERGii Steindachner. 



Gymnocliaracinus (5«-_o-/i!' Steindachner, SB. Akad. Wiss. Wien, CXII, 20, 1903. (A brook from 



southern Argentina, exact locality not given.) 



Head 4 ; depth 3 ^^ ; D. 1 1 ; A. 13 ; V. 6-7. Snout blunt, jaws equal ; maxillar>' not reach- 

 ing to middle of eye ; width of head 1.5 in its length ; eye 4 in head ; interorbital nearly 3 ; base 

 of dorsal 2.4 in the head, its height 1.75 ; ventrals 2.4; base of anal less than twice in head; 

 brown, a dark brown lateral "band from the head to the caudal. 



- The African genera are interpolated here although they very probably underwent a separate 

 evolution and their position in the key does not represent their relationship. 



