12 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. XII. 



Color in alcohol grading from deep purplish brown along the mid- 

 dorsal line to yellowish white below; the scales on the back and upper 

 sides become abruptly darker basad; a number of black spots usually 

 present along the upper sides; the head is dark above, on the opercle, 

 and below the eye. Paired fins clear; median fins dusky on their inter- 

 radial membranes. 



(athi, named for the Athi River, in which the types were collected.) 



Barbus helleri sp. nov. 



Plate II 



Type specimen, a mature female 51.5 mm. long to the caudal base, 

 Cat. No. 6105. The type description is supplemented by measurements 

 of 10 paratypes, mature males and females varying in length from 48 to 

 51 mm. (Cat. No. 6114). Ninety-two other specimens were examined, 

 26 to 48 mm. in length (Cat. No. 6115). 



Barbus helleri is closely related to Barbus longicauda of the Zambesi 

 River (recorded by Boulenger from the Nairobi River, a tributary of the 

 Athi), and to B. thikensis of the Tana system (recorded also from Lake 

 Victoria) . From longicauda, 1 helleri is distinguishable by its pronounced 

 lateral band coloration, by the shorter pectoral fin, and by the much 

 lower dorsal spine, which is constantly shorter than the postrostral 

 length of the head ("as long as or a little shorter than head" in longi- 

 cauda). From thikensis, helleri differs in the narrower interorbital, 

 lower dorsal spine, smaller scales, and apparently in the more distinct 

 lateral band, and in the constant presence of the caudal spot. B. 

 amphigramma is another similar species, but has a smooth dorsal 

 spine. 



Depth of body, 3.9 (3.6 to 4.1) in length to caudal base; length of 

 caudal peduncle, from anal base to end of last vertebra, 2.1 (1.75 to 2. 2) 

 times its least depth. Extreme length of head 3.75 (3.45 to 3.85) ; snout 

 in head, 4.0 (4.0 to 4.2); eye, 4.0 (4.0 to 4.2); least interorbital width, 

 3.0 (2.9 to 3.6); upper jaw extending to vertical from front of orbit, 

 being about as long as the snout, and about as long as the width of the 

 terminal or subinferior mouth; lips not conspicuously developed, the 

 lower with a frenum. Anterior barbel as long as the pupil, or shorter; 

 posterior barbel as long as eye, rarely a little longer, often only two- 

 thirds as long as eye. 



1 The specimens recorded under this name by Gilchrist and Thompson (Ann. S. 

 Afr. Mus., II, 1913, p. 407) do not agree with the descriptions of this species, and 

 probably represent another species. From these specimens B. helleri is apparently 

 distinguished by the more robust body; smaller eye; in having usually 4 scales from 

 the lateral line to the ventral, and usually 16 around the caudal peduncle; and in the 

 coloration. 



