POLYPTERUS. 9 



ripening of the eggs from June to September, but, since the spawning-seasons of nearly 

 all Nile Fishes correspond in a rough way, there is evidence that Polypterus probably 

 breeds during, or just after, the inundation of the Nile. Several specimens killed by 

 the influx of salt water in the low Nile at Toela, some 30 miles from the sea, in the 

 beginning of August, were heavily laden with eggs. 



The same observer has also noticed that, in spite of its lung-like air-bladders, 

 Polypterus will not survive more than three or four hours out of water, and only then 

 under the most favourable conditions — that is, covered with damp grass and weeds. 



The eggs, when ready to be shed, are blackish in their upper half and whitish below, 

 and measure only 1^ millimetres. 



2. POLYPTERUS ENDLICHEM. 

 (Plate II.) 



Polypterus endlicheri, Heckel, Russegger's Reise Egypt, iii. p. 310, pi. xxii. fig. 1 (1849) ; 



A. Dumeril, Hist. Poiss. ii. p. 393, pi. xxiii. ftg. 3 (1870) ; Steindachner, Denkschr. Ak. 



Wien, xliv. 1882, p. 52, pis. viii. & ix. fig. 2 ; Boulenger, Ann. & Mag. N. H. (7) ii. 1898, 



p. 418, and Proc. Zool. Soc. 1902, i. p. 124, pi. xi. fig. 2 ; Werner, Zool. Jahrb., Syst. xxi. 



1904, p. 271. 

 Polypterus senegalensis, part., Giinther, Petherick's Trav. ii. p. 268 (1869). 

 Polypterus bichir, part., Giinther, Cat. Fish. viii. p. 326 (1870). 



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

 fifths to five and two-fifths times. Body more or less distinctly flattened, at least in front. 

 Head once and a half to once and four-fifths as long as broad, much flattened, with 

 supero-lateral eyes and flat or slightly concave interorbital region; lower jaw projecting 

 slightly beyond the upper ; length of snout five to seven times in the length of the 

 head ; eye nine (young) to fifteen times in the length of the head, twice and one-sixth 

 (young) to three and two-thirds times in the interocular width ; the latter more than 

 the distance between the eye and the spiracle ; cleft of the mouth not extending much 

 beyond the anterior third of the head ; nasal bones in contact on the median line in 

 the adult ; a series of four to six shields between the postorbital and the spiracular 

 shields ; suboperculum much larger than the eye. Gular plates twice to twice and 

 a half as long as broad. Dorsal fin with 11 to 14 spines, followed by 18 to 21 

 articulated dorsal and caudal rays ; anterior spines not or but feebly overlapping when 

 folded, three to five times as long as broad ; the first spine corresponding to the 

 twelfth to sixteenth transverse series of scales. Anal fin with 15 to 18 rays. Pectoral 

 fin with 40 to 45 rays, reaching to or beyond the vertical of the first spine of the 

 dorsal. Scales smooth or more or less rugose with wavy longitudinal striae, in 50 to 58 

 transverse series, 42 to 46 round the body. 



Grey or greyish olive above ; four to six more or less regular broad blackish bands 



c 



