1894.] ±06 [Cope. 



on the posterior part of the body, one lateral line scale corresponds to two 

 transverse rows. Thus the transverse rows number 73, while there are 

 only 40 in the lateral line. Fin radii, I). XX. 12; A. III. 9 ; V. I. 5 ; 

 P. 17. Color brownish above and yellowish below in alcohol. Sides of 

 body and head with dorsal and anal fin rather spar.«ely spotted with 

 small black spots. A much larger black spot at the base of the caudal 

 fin, which is not light bordered. A black band from the eye, the opercu- 

 lar border, and another very distinct one from the eye downwards across 

 the cheek. Paired fins uniformly yellowish. 



Total length, 196 mm.; length to base of caudal fin, 168 mm.; length 

 to base of anal, 115 mm.; length to base of ventral, 89 mm.; length to 

 base of dorsal (axial), 53 mm. 



The number of transverse rows of scales is intermediate in the genus, 

 while the number of those traversed by the lateral line is smaller than is 

 mentioned by authors as occurring in any known species. The promi- 

 nence of the lower jaw approximates a character of the C. lucius Cope, of 

 the upper Amazon, but in that species the top of the head is flat and hori- 

 zontal and not convex and decurved. The scales are also larger. 



But three specimens of this fish were taken by Mr. Smith. The small- 

 est measures 137 mm. in total length and diff"ers as a younger individual 

 in the larger eye, which enters the head 4.75 times, and equals the inter- 



9 



orbital width. Radii, D. XXII. 13 ; A. III. 9. Scales ji , the transverse 



22 



series twice as numerous as those of the lateral line posteriorly, and three 

 times as numerous anteriorly. Besides the black specks there is a row of 

 eight dusky spots on the side of the body. 



Geophagus gymnogenys Hense!., Arch, fur Naturgexch. , 1870, p. 61 ; 

 Von Jhring, Susswasser Fische von Rio Grande do Sul, 1898, p. 31. 

 I find four species of Geophagus in the Smith collection, which difier 



as follows : 



a. Cheeks naked or nearly so. 



Profile nearly straight ; eye one-third head ; caudal fin emarginate ; anal 

 soft rays. 8; body oval; smaller G. gymnogenys. 



Profile of skull strongly convex at orbit ; eye one-third head ; outline of 

 body contracting from first dorsal spine posteriorly ; caudal fin trun- 

 cate ; anal soft rays, 8 ; smaller O. cawiurus. 



aa. Cheeks scaly. 



Profile straight, preorbital bone wider; caudal fin truncate; anal with 

 eight soft rays ; eye one-fourth head ; 1. 1., 25 ; smaller.. G. hrachyurus. 



Profile straiglit ; preorbital bone much wider ; eye more than four times 

 in head ; body oval ; 1.1., 38 ; anal with nine soft rays ; caudal fin 



rounded ; larger G. brasiliensis. 



In each of the four species of Geophagus here described, the inferior 



bounding fold of the inferior lip is interrupted at the middle line. The 



