MAKCUSENIUS. 47 



four and two-thirds to five and two-thirds times in the length of the head ; teeth small, 

 bicuspid, truncate when worn down, 5 in the upper jaw, 6 in the lower; nostrils on a 

 line with the lower border of the eye, nearer the latter than the end of the snout ; eye 

 moderate, as long as or a little longer than the snout, about two-thirds the interocular 

 width. Dorsal fin with 34 to 36 rays, as long as or a little shorter than its distance from 

 the head ; anterior rays longest, forming a point. Anal fin with 24 to 26 rays, originating 

 below fourteenth to sixteenth rays of dorsal, equally distant from the base of the ventral 

 and that of the caudal, or a little nearer the latter ; anterior rays longest, especially in 

 the males, in which the anterior half of the fin forms a rounded lobe. Pectoral fin 

 pointed, subfalcate, nearly as long as the head, once and two-thirds to once and three- 

 fourths the length of the ventral and extending beyond the base of the latter. Caudal 

 fin scaled at the base, with pointed lobes. Caudal peduncle twice and a half to three 

 times as long as deep, as long as or a little shorter than the head. 55 to 65 scales in 

 the lateral line, -^^ in a transverse series on the body, ^|| in a transverse series 

 between dorsal and anal, 12 round caudal peduncle ; many of the scales on the sides 

 below the lateral line with the free border more or less distinctly notched. 



The fish, in spirit, is brown above, silvery white below, more or less speckled with 

 darker ; an ill-defined dark bar, extending obliquely from the origin of the dorsal fin 

 to that of the anal, is sometimes present ; the dorsal fin, and sometimes also the anal, 

 brownish in front. 



The largest specimen measures 220 millimetres. 



This species was described from four specimens obtained at Khartum by Petherick, 

 which had been referred by Giinther to Mormyrus discorhynchus of Peters, from the 

 Lower Zambesi and Lake Nyassa. Mr. Loat obtained five specimens at Wad Medine, 

 Blue Nile, 6-13.10.01, and two at Fashoda, White Nile, 20.3.01. 



Marcusenius discorhynchus resembles M. petherici very closely, but differs in the 

 shorter caudal peduncle surrounded by 14 scales, and in the greater distance between 

 the dorsal fin and the head. M. budgetti, Blgr., recently described from the Niger 

 Delta, is still more nearly related to M. petherici, differing only in the larger scales on 

 the body, there being ^ in a transverse series in front of the ventral fins, and ™ 

 between the dorsal and anal fins. And, finally, the Mormyr recently discovered in 

 Lake Tanganyika and described as M. tanganicanus, Blgr., may be regarded as exactly 

 intermediate between M. petherici and M. discorhynchus. Details of these allied 

 species are given in the annexed table, for the purpose of comparison. 



