52 



M OEM YE ID /E. 



4. PETROOEPHALUS BALLAYI. 



Mormyvvs catostoma (non Giintli. 1866), Giinth. Ann. & Mag. N. H. (3) xx. 1867, 



p. 166. 

 PetTocephahis balayi, Sauv. Bull. Soc. Philoni. (7) vii. 1883, p. 159 ; Bouleng. 



Proc. Zool. Soc. 1898, p. 789, and Poiss. Bass. Congo, p. 72 (1901) ; Pcllegr. 



Bull. Soc. Philom. (9) ix. 1907, p. 20. 

 Mormyrus amhlystoma, Giinth. Ann. & Mag. N. II. ((5) xvii. 1896, p. 281, 



pi. xiv. fig. A. 



Depth of body 2f to 3 times in total length, length of head 3i to 

 3-f times. Head as long as deep, with convex upper profile ; snout very 

 short, ^ to -1- length of head, obliquely truncate, projecting beyond mouth ; 

 mouth below anterior border or centre of eye, its width -3- length of head ; 

 teeth bicuspid, 20-24 in upper jaw, 30-36 in lower; nostrils above 

 lower border of eye ; eye large, its diameter greater than length of 

 snout, f interorbital width. Dorsal 23-2-5, originating above 4th or 5th 

 ray of anal, its length nearly J its distance from head and equal to its 



Fie. 37. 



ifVrpjjs 





m££ 



m@&" 



¥ 



Petrocephalus ballay i. 

 Type of M. amhlystoma, after Giinther (Ann. & Mag. N. H. 1896). 



distance from caudal. Anal 28-30, slightly nearer base of caudal than 

 base of ventral. Pectoral pointed, f- length of head, If length of 

 ventral, extending beyond base of latter. Caudal scaled at the base, 

 with pointed lobes, Caudal peduncle 2J to 3 times as long as deep, 

 f- to j length of head. 35-37 scales in lateral line, jp^ in transverse 

 ■series on the body, jj- in transverse series between dorsal and anal, 



