THE AMERICAN TETRAGONOPTERINAE. 75 



Origin of dorsal a little in advance of the middle, its height four in the length; 

 caudal large, the lower lobe slightly longer, about one third of the length; anal 

 basis equals distance from dorsal to caudal, its origin equidistant from tip of 

 snout and base of middle caudal ray; anal emarginate, the highest anterior ray 

 twice the height of the fifteenth ray; ventrals reaching beyond origin of anal, 

 equidistant from tip of snout and last third of the anal; pectorals reaching to 

 middle or the second third of the ventrals. 



A large, horizontally oval, humeral spot, nearly two thirds as long as the 

 head; a silvery lateral stripe not much more than half the width of the pupil; 

 general color, including all the fins dark, the fins with numerous pigment cells. 



Vertebrae 12 +20. 



Alimentary canal not equal to the total length. Contains ants in the one 

 dissected. 



Measurements of eleven specimens M. C. Z. 20909. 



Specimen Dorsal Anal Length Depth Head Eye 



mm. mm. mm. mm. mm. 



1 11 34 SO 3S 21 S.5 8 5'-5 2 5M3 4 



2 11 36 81 38 20 8 7 5-5 5-1 



11 11 36 59 25 15 7 5 5-5 8-7 



6. MOENKHAUSIA CHRYSARGYREA (Giillther). 



Plate 6, fig. 3; Plate 100, fig. 9, 10. 



Tetragonopterus chrysargyreus Gunther, Cat. fishes Brit, mus., 1864, 5, p. 328 (Essequibo); Eigenmann 

 & Eigenmann, Proc. U. S. N. M., 1891, 14, p. 53; Ulrey, Ann. N. Y. acad. sci., 1895, 8, p. 281. 



Moenkhausia chrysargyrea Eigenmann, Rept. Princeton univ. exped. Patagonia, 1910, 3, p. 45. Mem. 

 Carnegie mus., 1912, 5, p. 323. 



Moenkhausia chrysargyrea leucopornis Fowler, Proc. Acad. nat. sci. Phil., 1914, p. 245 (Rupununi). 



Habitat. — Essequibo, Amazons. 



1 Front row. ! Second row. 3 On one maxillary. * On the other. 



