PETEOCEPHALUS. 47 



2. PETEOCEPHALUS. 



Petroceplialm, part., Marcusen, Bull. Ac. St. Petersb. xii. 1854, p. 14, and M6in. 



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

 Mornvjnts, p-irt., Gunth. Cat. Fish. vi. p. 214 (1866). 

 Petroaephalus, Grill, Proc. Ac. Philad. 1862, 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 10-36 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. Vertebrfe 42-44 (9-12 + 4-6 

 + 27-29). 



Nile and Tropical Africa. 



Synoj^sis of the Species. 



I. Anal originating more or less ia advance of dorsal, which has at least 20 raj'S. 

 A. Diameter of eye greater than length of snout. 

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



14-22 



Di:imeter of eye |-| interorbital width; teeth ^^zgo 



1. P. lane, Lacep., p. 48. 



2. P. sauvagii, Blgr., p. 49. 



3. P. ansorgii, Blgr., p. 51. 



10-12 scales round caudal peduncle 



Diameter of eye equal to interorbital width 



{gg^lj ^"~-° ; 12 scales round caudal peduncle 



28—30 1 r\ 



Diameter of eye 1-^ interorbital width ; teeth g^ 



8 scales round caudal peduncle .... 



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 ^^ . . . LP. hallayi, 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 j-g-^g. 



D. 22-26 ; A. 30-35; L. 1. 38-43 6. P. hovei, 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. 3.5-38 8. P. stuhlmanni, Blgr., p. 56. 



b. 16 scales round caudal peduncle. 



D. 20-22 ; A. 25-29 ; L. 1. 37-40 ; teeth ~ . 9. P. catostoma, Gthr., p. 57. 



