74 



MEMOIRS OF THE CARNEGIE MUSEUM. 



caudal rays. The base of the anal in specimens from Porto Alegre, Cachoeira, 

 and Maldonado is but little, if any, longer than the caudal peduncle. In all but 

 one of the Cacequy specimens it is equal to the caudal peduncle and middle caudal 

 rays, and usually contains twenty-two rays, more rarely twenty-one, twenty-three, 

 or twenty-four. 



There may be two, possibly three, varieties in the material at hand. If so, 

 they may be distinguished by the following characters : 



a. Base of anal less than caudal peduncle and middle caudal rays. 



b. A. 18-23, most frequently 19-20; most frequently 5-5 teeth in the premaxillaries, less frequently, 4-4 

 or 4-5 or 5-6; base of anal equal to the length of the caudal peduncle. Caudal spot usually well 



defined. Nos. 6815, 6817, 6818 (Rio Grande do Sul) 39. monodon Cope. 



bb. A. 17-22, most frequently 19; usually 5-5 teeth in the premaxillary; base of anal equal to the length 

 of the caudal peduncle or a little longer. Nos. 846, 847, 20698 and 20699, M. C Z. (Uruguay 



river basin) 38. interruptus Jenyns. 



aa. A. 21-24, most frequently 22; 4-4, or 4-5 teeth in the premaxillary; base of anal equal to length of caudal 

 peduncle and middle caudal rays. Caudal spot diffuse. No. 6816 (Cacequy). 



40. ibicuhiensis Eigenmann var. nov. 



Table Showing in Detail the Number of Specimens with the Indicated Number of Premaxillary 



Teeth and of Anal Rats. 



41. Cheirodon notomelas, sp. nov. (Plate XII, fig. 2.) 

 6812, C. M., type, 9 , 35 mm. ; 6813a-q, C. M., paratypes, nineteen, largest 40 mm. 

 collected in a lake, four miles from Miguel Calmone, Tiete basin. Oct. 11, 

 1908. Haseman. 

 6814, C. M., one, 30 mm. Piperao Azul, lake twelve miles from Tiete. Oct. 7, 



1908. Haseman. 

 Head 4; depth 2.5-2.66; D. 10 or 11; A. 20-22; scales usually 33 (32-34), 

 six to eight with pores; eye about 2.5 in the head, equal to the interorbital; depth 

 of caudal peduncle about equal to its length. 



Compressed, dorsal and ventral profiles equally curved; preventral area rather 

 flat with a regular median series of eleven scales ; predorsal area narrowly rounded 

 with a median series of ten or eleven scales; occipital process broad, reaching one- 

 seventh to dorsal, bordered by two and one-half scales on each side; skull convex; 



