536 PROCEEDINGS OF THE ACADEMY OF [-^uly, 



the lower lobe of the caudal fin. The caudal is obliquely truncate or 

 slightly emarginate, the upper lobe being the longer. Sides with ob- 

 scure cross-bars, otherwise as in the type. 



107. Geophagus pappaterra Heckel. 



One specimen (185), from the Laguna near the Arroyo Trementina. 

 D. XVI, 10; A. Ill, 6; lat. line 19+10. 



108. Biotodoma trifasciatus sp. nov. 



Type No. 10,066, a single small specimen, 29 mm. (225), Arroyo 

 Chagalalina. 



Head 3; depth 2|; D. X, 6; A. Ill, 5; lat. line, 7 + 9. 22 scales along 

 median line. Streak along base of dorsal; lateral band from tip of 

 snout to caudal spot; a narrow, well-defined oblique band from lower 

 margin of pectoral to origin of anal and continued to tip of first ray 

 dark; an oblique bar from eye down and back, outer rays and most of 

 the base of the ventrals jet black, the rest of the fin colorless. Pec- 

 torals and caudal dusky. Dorsal with a black margin; anal dusky 

 except the streak mentioned above, which is black. Fins yellow in 

 life. Eye nearer snout than gill-slit, f in snout, about 2| in head. 

 Supplementary flap of first gill-arch well developed. Scales large; 

 lateral line not well developed, the anterior part with only nine devel- 

 oped tubes, the last one of which is under the anterior half of the dorsal, 

 only a partial scale between the last developed tube and the dorsal. 

 Pectorals reaching to vent, ventrals to anal, soft dorsal and anal to 

 caudal. 



109. Achirus jenynsii Gi'mther. Lenguado, Pira Kigua. 



Six specimens (38, 42, 143), Asuncion, Rio Paraguay. March, 1900. 



Bibliography. 



The collection and study of fishes has been more active in the southern part of 

 South America during the last fifteen years than in the northern. Several papers 

 have appeared during this time on the fishes of Rio Grande do Sul, a larger 

 number dealt with the fishes of one part or another of the La Plata system. None 

 of these papers offer a comprehensive account of the fishes of the system, being 

 rather reports on definite collections. We give below a list of the papers dealing 

 with fishes of the La Plata basin published since 1890. The earlier papers are 

 given in Eigenmann and Eigenmann, 1891. 



Berg. 1895. Sobre Feces de Aqua Dulce, A7in. Mus. Buenos Aires, IV, 



121-165. 

 1897. Contr. al Conoc. de los Peces Sudamericanos, Ann. Mus., V, 263-302. 

 1899. Communicaciones Ictiologicas I, II, III and IV. Com. Mus Buenos 



Aires. I, 9-13. 91-97, 165-174, 293-311. 



