POLYPTEEUS. 



well-preserved material obtained in the Gambia, concludes that it is rather homologous 

 with the external gill of larval Dipneusti and Batrachians, which have properly an 

 external and an internal gill to each visceral arch. 



Although among the most characteristic fishes of the Nile, the Polypteri do not 

 appear to have been depicted by the ancient Egyptians. 



Synopsis of the Species. 



Dorsal fin with 14 to 18 spines ; inter orbital region slightly convex ; 

 suboperculum larger than the eye ; 63 to 7.0 scales in a longitudinal 

 series, 46 to 54 round the body 1. P. bichir, Geoffr. 



Dorsal fin with 11 to 14 spines ; interorbital region flat or slightly 

 concave ; subopercnlum larger than the eye ; 50 to 58 scales in a 

 longitudinal series, 42 to 46 round the body 2. P. endlicherl, Heck. 



Dorsal fin with 8 to 11 spines; interorbital region very convex ; sub- 

 operculum not larger than the eye; 53 to 61 scales in a longitudinal 

 series, 34 to 40 round the body , 3. P. senegalus, Cuv. 



1. POLYPTERUS BICHIR. 

 (Plate I.) 



Polypterus bichir, Geoffroy, Ann. du Mus. i. 1802, p. 57, pi. v v and Descr. Egypte, Poiss. p. 4, 

 pi. iii. (1809) ; Guichenot, Mag. Zool. 1839, Poiss. p. 10 ; Giinther, Petherick's Trav. ii. 

 p. 267 (1869); A. Dumeril, Hist. Poiss. ii. p. 391, pi. xxiii. fig. 1 (1870); Schweinfurth, 

 Herz. Afr. i. p. 253, fig. (1874) ; Steindachner, Denkschr. Ak. Wien, xliv. 1882, p. 52, pis. viii. 

 & ix. fig. 1; Boulenger, Ann. & Mag. N. H. (7) ii. 1898, p. 417 ; S. Flower, Proc. Zool. Soc. 

 1900, p. 969; Werner, Zool. Jahrb., Syst. xxi. 1904, p. 271. 



Polypterus bichir, part., Giinther, Cat. Fish. viii. p. 326 (1870) ; Vinciguerra, Ann. Mus. Genova, 

 (2) xix. 1898, p. 243. 



Depth of body seven to nine times in the total length, length of head four and one- 

 fourth to five and two-thirds times. Head twice or nearly twice as long as broad, 

 rather strongly flattened, with superolateral eyes and slightly convex interorbital 

 region; lower jaw projecting slightly beyond the upper; length of snout five to seven 

 times in the length of the head ; eye eight and a half (young) to thirteen times in the 

 length of the head, once and five-sevenths (young) to twice and four-fifths in the 

 interocular width ; the latter less than the distance between the eye and the spiracle ; 

 cleft of the mouth extending beyond the anterior third of the head ; nasal bones in 

 contact on the median line in the adult ; a series of four to seven shields between the 

 postorbital and the spiracular shields ; suboperculum much larger than the eye. 

 Gular plates twice and a half to three times as long as broad. Dorsal fin with 14 to 

 18 spines, followed by 20 to 23 articulated dorsal and caudal rays; spines overlapping 

 when folded down, four to eight times as long as broad, the first corresponding to the 



