eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 331 



Type, 50 mm. Lama Stop-Off. (Carnegie Museum Catalog of Fishes No. 

 1042.) 



Cotypes, two hundred and three specimens, 20-50 mm. Lama Stop-Off. 

 (C. M. Cat. No. 1043a-z; I. U. Cat, No. 11735.1 



Cotj'pes, fifty specimens, 28-46 mm. Cane Grove Corner. (C. M. Cat, 

 No. 1044a-j; I. U. Cat. No. 11736.) 



Cotypes, twenty-one specimens, 35-49 mm. Maduni Stop-Off. (C. M. 

 Cat. No. 1045«-e; I. U. Cat. No. 11737.) 



This species is very abundant in the canal from Cane Grove Corner to Maduni 

 Creek Stop-Off. It is named for Mr. Saint Aubyne, whose guest I was at Lama 

 Stop-Off, and who did everything in his power to further the interests of my fishing 

 expedition. 



This species is placed in the genus with Pristella riddlei, because in the technical 

 characters they agree. There is every probability that they are not immediately 

 descended from the same ancestor. 



Head 3.75; depth 3.5; D. 10; A. 16-18; scales 6-31 to 33-3, rarely 4; seven to 

 nine pores in the lateral line; eye 2.33; interorbital 3. 



Elongate, heavy forward; ventral profile curved more than the dorsal, which 

 is nearly straight to the dorsal fin, not depressed over the eye; preventral area broad, 

 rounded, postventral area keeled; predorsal area narrowly rounded. 



In life the base of the upper caudal lobe is red, that of the lower yellow, and 

 there is some yellow on the under side of the caudal peduncle and in front of the 

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

 rays. A dark line in front of the dorsal, and a series of spots behind it. A well- 

 defined humeral spot on and over the second and third scales of the lateral line. 



Hemigrammus Gill. 44 

 Hemigrammus Gill, Ann. Lye. Nat. Hist. N. Y., VI, 1858, 60. 



Type, Hemigramvius unilineatus Gill. 



Small or minute Tetragonopterid characins with two rows of notched teeth 

 in the upper jaw, a single row of similar teeth on the mandible, and a few teeth 

 on the upper part of the maxillary; lateral line incomplete; caudal scaled. 



This genus is Mcenkhausia with an incomplete lateral line. 



Key to the Guiana Species of Hemigrammus. 

 a. Dorsal with a well-defined black spot. Anal with an intense black bar from a little in front of the base of 

 first ray to the tips of the fourth and fifth rays. Humeral spot vertically elongate, often faint and 



44 The account of this genus is compiled from a manuscript by Mrs. Marion Durbin Ellis. 



