Eigenmann: The Serrasalmin.e and Mylin^. 267 



5639 a. C. M. One, 92 mm. Berlin, Rio Mamore, Sept. 15, 1909, 

 Haseman. 



5640 C. M. One, 147 mm. San Joaquin, Bolivia, Sept. 4, 1909. 

 Haseman. 



?5629 C. M. 44 mm. and 5630 C. M. Nineteen, largest 48 mm. 

 Villa Hays, Paraguay, April 13, 1909. Haseman. 



Description of Adult. 

 Head 3-5-3-75; depth li-if ; D. 14, 15, 16, 16; A. 30, 33, 34, 37. 

 Abdominal serrae, 45, 49, 50. 

 Scales 50-86-40, supplementary scales numerous. 



XI. Genus Metynnis Cope. 

 34. Metynnis guaporensis sp. nov. (Plate LIV.) 



5729 a-c. C. M. 73-99 mm. Maciel, Rio Guapore, July 26, 1909. 

 Haseman. 



The largest the type, 



5730 a. C. M. 51 mm. San Joaquin, Bolivia, Sept. 4, 1909. Hase- 

 man. 



Head 3-3.25; depth ly, equals body and opercle; D. 18-20; A. 

 41-44; serrae 29-32; eye 3.5 in head, interorbital 2.75; gill-rakers long, 

 slender, those of the middle of the upper and longer, nearly as long 

 as eye, 30 + 35. Scales 90. 



Compressed; dorsal profile rising rapidly from the base of the occi- 

 pital process to the predorsal spine; ventral profile nearly regularly 

 arched to the anus. 



Occipital process reaching four-tenths the distance from its base 

 to the dorsal; second suborbital bordered by a naked area about 

 equal to its own width. 



Ventral spines rather strong, those behind the ventrals widened 

 at the tip with anterior and posterior points; origin of the dorsal 

 equidistant from snout and end of scales at base of middle of caudal; 

 the second and third rays prolonged, 2.5 in the length, reaching about 

 to the middle of the base of the adipose; base of adipose about equal 

 to the postorbital portion of the head; depth of caudal peduncle 

 equals the length of the head; caudal lobes nearly equal to length of 

 head; distance of origin of anal from tip of snout a little less than the 

 origin of the adipose from the same point; margin of anal nearly 

 straight, without a lobe; origin of ventrals about equidistant from 



