THE AMERICAN TETRAGONOPTERINAE. 77 



ray three in the length; ventrals a little nearer to tip of snout than the dorsal, 

 about equidistant from tip of snout and end of anal; ventrals reaching to anal 

 somewhat shorter in old specimens; pectorals reaching two scales beyond 

 ventrals; anal emarginate, the highest ray about two thirds the length of the 

 base. Iridescent silvery. A deep lying, well-defined, horizontally oval, circular 

 or rhomboidal, black, humeral spot over the space between the fifth to the eighth 

 scale of the lateral line and at least the width of a scale removed from it; a few 

 scattered cells nearer the surface extend from the front of the spot across 

 the lateral line; humeral spot surrounded by a light court behind which there is 

 a faint vertical bar; a narrow silvery lateral fine, its width equal to about one 

 fourth the length of the maxillary; no caudal spot; sides variously dotted with 

 chromatophores. In the Tumatumari specimens the scales of the abdomen are 

 margined with dark, there being faint streaks following the rows of scales. Scales 

 of the second row below the dorsal each with an oblique dark band noticeable 

 only with a lens; outer margin of pectoral and ventral dark; middle of anal 

 lobe and bases of the remaining rays yellow; dorsal rays each tinged with yellow 

 at its middle, pectoral tinged with yellow; upper part of iris red. Vertebrae 

 11 + 19. 



Posterior section of air-bladder about twice as long as anterior; its width 

 about equal to the eye; bent down behind and reaching to near the origin of the 

 anal. 



7. Moenkhausia comma Eigenmann. 



Plate 6, fig. 2. 



Moenkhausia comma Eigenmann, Bull. M. C. Z., 1908, 62, p. 102 (Cudajas); Rept. Princeton univ. 

 Exped. Patagonia, 1910, 3, p. 437. 



One specimen 20972 part Type 77 mm. Cudajas Thayer and Bourget. 



A second specimen in very bad condition of the same length and from the 

 same place. 



This species can readily be distinguished by its elevated dorsal, and the 

 peculiar humeral spot. 



Head 3.4; depth 2 + ; D. 11; A. 26; scales 6-32(?)-5. Eye 2.5; equal to 

 interorbital. 



Deep, compressed, subrhomboidal, the anal basis much steeper than the 

 predorsal profile. Profile very slightly depressed over the eye. Preventral 

 area narrowly rounded, the lateral series of scales without a distinct bend. 

 Postventral area compressed; predorsal area narrowly compressed and keeled, 

 with eight median scales between occipital process and dorsal. 



