The Freshwater Fishes of South Africa. 



327 



3. MAECUSENIUS. 



Petrocephalus, part., Marcusen, Bull. Ac. St. Petersb., xii., 1854, 

 p. 14. 



Marcusenius, Gill, Proc. Ac. Philad., 1862, p. 129; Bouleng., Cat. 

 Freshw. Fish. Afr., i., p. 60 (1909). 



Mormyrus, part., Gimth., Cat. Fish., vi., p. 214 (1866). 



Teeth only in the middle of the jaws, truncate or notched; minute 

 conical teeth on parasphenoid and tongue ; mouth inferior or sub- 

 inferior, below level of eyes ; nostrils widely separated. 



Key to Species. 



Anal originating in advance of dorsal. 



Teeth f ; D. 16-17, A. 22 ; Lat. 1. 53 . . 

 Teeth ; D. 17, A. 23 ; Lat. 1. 48-50 



Dorsal originating in advance of anal. 



Teeth ; D. 30-36, A. 23-27 ; Lat. 1. 65-70 . . 



1. M. isidori. 

 '2. M. castelnaui. 



3. M. discorhynchns. 



MARCUSENIUS ISIDORI, C. and V. 



Mormyrus isidori, Cuv. and Val., Hist. Poiss., xix., p. 285 (1846). 



Petrocephalus isidori, Marcusen, Bull. Ac. St. Petersb., xii., 1854, 

 p. 14. 



Marcusenius isidori, Bouleng., Proc. Zool. Soc., 1898, p. 798, and 

 Cat. Fresh. Fish. Africa, i., p. 76 (1909). 



I : -:---::,; -;.v. u 



u i'^ffjM*:'^: - .;.-.-- 





FIG. 5. Marcusenius isidori. 



Teeth bicuspid, 8 in the upper 8 in lower jaw. Depth of body 3 

 to 3^ times in total length excluding caudal, length of head 4 to 4| 

 times ; head as long or nearly as long as deep ; snout i to T 3 - length 

 of head, rounded, projecting beyond mouth; mouth situated below 

 nostrils, its width 3f to 4^ times in length of head ; anterior 

 nostril in a line with centre of eye, midway between eye and point 



