Eigenmann: The Expedition to British Guiana. 25 



of the premaxillary of which the middle one is withdrawn from the 

 line of the rest. Inner series of teeth large, multicuspid, graduate. 

 Maxillary with numerous similar teeth ; lower jaw with four or five 

 graduate, multicuspid teeth in front and minute ones on the side. 



Gill rakers about 6 -f IX - 



Scales thin, not conspicuously regularly imbricate ; each scale with 

 several nearly parallel horizontal striae ; anal sheath composed of a 

 single row of cells along the front of the fin ; caudal lobes scaled for 

 about one-eighth of their length. 



Origin of ventrals a little nearer tip of last anal ray than snout, 

 slightly in advance of the dorsal ; penultimate dorsal ray more than 

 half the length of the longest which is 3J in the length. Anal 

 emarginate, ventrals reaching anal ; pectorals not to ventrals. 



In life base of upper caudal lobe red, base of lower caudal lobe 

 yellow, some yellow on under side of caudal peduncle and in front of 

 anal. A circular spot about as large as eye on base of middle caudal 

 rays. A dark line in front of dorsal, a series of spots behind it. A 

 well-defined humeral spot on and over the second and third scales 

 of the lateral line. 



Genus Deuterodon Eigenmann. 



Deuterodon pinnatus sp. no v. 



Type, 62 mm. (No. 1046 Carnegie Museum Catalog of Fishes.) 

 Amatuk, Lower Potaro River. 



Cotypes, 25 specimens, 32-75 mm., Amatuk, Potaro River. (C. 

 M. Cat. No. 1047, 2-e\ I. U. Cat. No. 11738.) 



Cotypes, 2 specimens, 36-40 mm., Konawaruk, Essequibo River. 

 (C. M. Cat. No. 1048 ; I. U. Cat. No. 11739.) 



Cotypes, 19 specimens, 21-43 mm -> Warraputa Cataract, Essequibo 

 River. (C. M. Cat. No. 1049, a-c ; I. U. Cat. No. 11740.) 



Distinguished from all other Tetragonopterids by the pinnate black 

 markings of the sides. 



Head 4-4.3 ; depth 2.5-2.7 ; D. 10 or 11 ; A. 24-25, rarely 27 ; 

 scales 6-36 or 37-4 or 5. 



Compressed, subrhomboidal, profile slightly depressed over the eye; 

 preventral area rounded, the scales large, a nearly regular median 

 series ; postventral area narrowly rounded, the anus directly in front 

 of the anal ; predorsal area narrowly rounded, with a median series of 

 about nine scales. 



