PETR0CEPHALTJ9. 47 



2. PETROCEPHALUS. 



Pelrocepludm, part., Marcusen, Bull. Ac. St. Petersb. xii. 1854, p. 14, and Mem. 



Ac. St. Petersb. (7) vii. 1864, no. 4, p. 111. 

 Mormyrus, part., Giinth. Cat. Fish. vi. p. 214 (18G6). 

 Petroceplialus, Grill, Proc. Ac. Philad. 18(32, p. 443 ; Bouleng. Proc. Zool. Soc. 



1898, p. 787, Poiss. Bass. Congo, p. 70 (1901), and Fish. Nile, p. 32 (1907). 



Teeth in the jaws bicuspid, forming a single complete series on the 

 entire edge of both jaws (10-26 upper and 16-35' lower) ; minute 

 conical teeth on the parasphenoid and on the tongue ; mouth inferior, 

 situated below the eyes. Nostrils close together, close to the eye. Body 

 short ; ventral fins nearer the pectorals than the anal. Dorsal and anal 

 fins usually not very unequal in length. Vertebrae 42-44 (9-12 + 4-6 

 + 27-29). 



Nile and Tropical Africa. 



Synopsis of the Species. 



I. Anal originating more or less in advance o£ dorsal, which has at least 20 rays. 

 A. Diameter of eye greater than length of. snout. 



1. D. 28-33 : A. 31-39 ; L. 1. 39-50. 



14— °° 



Diameter of eye §-£ interorbital width; teeth ^^n ; 



10-12 scales round caudal peduncle . . . 1. P. bane, Lacep., p. 48. 

 Diameter of eye equal to interorbital width ; 



teeth ^+^, ; 12 scales round caudal peduncle . 2. P. sauvagii, Blgr., p. 49. 

 Diameter of eye 1-i interorbital width ; teeth . ^ ; 



8 scales round caudal peduncle . .... .3. P. ansorgii, Blgr., p. 51. 



2. D. 20-28. 



■ - a. 10-12 scales round caudal peduncle. 



a. Base of dorsal at least as long as its distance from caudal. 

 D. 21-25 ; A. 28-30 ; L. 1. .35-37 ; 16-18 



scales between D. & A. ; teeth ^^s . . . i. P. ballayi, Sauv., p. 52. 

 D. 24-28 ; A. 30-34 ; L. 1. 38-45 ; 21-26 scales 



between D. & A. ; teeth ^-^ 5. P. simus, Sauv., p. 53. 



/3. Base of dorsal shorter than its distance from caudal; teeth 16 ; ^' 

 D. 22-26 ; A. 30-35 j L. 1. 38-43 . . . . . 6. P. bovei, C. & V., p. 54. 



D. 25 ; A. 38-39 ; L. 1. 41-44 7. P. keatingii, Blgr., p. 55. 



D. 20-22 ; A. 25-29 ; L. 1. 35-38 8. P. stuhlmanni, Blgr., p. 56. 



b. 16 scales round caudal peduncle. 

 D. 20-22 ; A. 25-29 ; L. 1. 37-40 ; teeth j|^ . 9. P. colostoma, Gthr., p. 57. 



