POLYPTERUS. 



1. POLYPTERUS. 



Geoffr. Ann. Mus. Paris, i. 1802, p. 57 ; A. Uum. Hist. Poiss. ii. p. 391 (1870) ; 

 Giinth. Cat. Fish. vii. p. 326 (1870) ; Bouieng. Poiss. Bass. Congo, p. 20 

 (1901), ami Fish. Nile, p. 2 (1907). 



Body more or less elougate, not serpentiform ; spines of the dorsal 

 fin bearing two or more articulated rays ; ventral fins present ; 

 suboperculum well developed ; teetli small, conical. 



Nile and Tropical xlfrica. 



St/nojysis of the Si)ecies. 



I. Man<lil)le projecting slightly heyonJ the snout ; sul (operculum much larger 

 than the eye ; pectoral extending as far as first dorsal s[)ine, or heyond ; 

 11-18 dorsal spines ; 11-15 scales l)et\veen occij)ut and first dorsal sjiine. 



A. GO-70 scales along the body, 4G-54 round the middle, 

 D. XIV-XVIII ; interorbital region slightly 



convex, 1| (y^i^n^g) f^ ^4 diameters of eye ; 



G3-70 scales in longitudinal series .... 1. P. Idchir, Geoffr., p. 0. 

 D. XIII-XV ; interorbital region quite flat, 2 

 (young) to 3| diameters of eye ; G0-G8 scales 

 in longitudinal series 2. I\ lapnuli't, Stdr., [>. 7. 



B. 50-59 scales along the body. 



D. XII-XIV ; interorbital region flat, not more 



than 3 diameters of eye ; usually a small 



azygous shield between the nasals, in the 



adult ; 4G-52 scales round middle of body . 3. P. congictis, Blgr., p. 9. 

 D. XI-XIV ; interorbital region flat or slightly 



concave, 2 (young) to 3^ diameters of eye ; 



no azygous shield on the snout; 42-4:6 scales 



round middle of body 4. i\ endlu'hen, Heck., p. 10. 



II. Both jaws equal in front, or snout [(rejecting beyond mandible; sub- 

 operculum not much larger, or even snuiller than the eye ; 5-11 dorsal 

 spines. 



A. 60-65 scales along the body, 42-16 round the middle; pectonil widely 

 separated from first dorsal spine : interorbital region flat or slightly 

 convex, 3 diameters of eye in adult ; 22-26 scales between occiput 

 and first dorsal spine. 

 D. IX-X ; body strongly depressed ; 44-46 scales 



round middle of body 5. P. weeksit, Blgr., p. 11. 



D. X-XI ; body feebly depressed, subcylindrical ; 



42 scales round middle of body ..... 6. P. ornatip'uutis, Blgr., p. 12. 



