o POLYPTEBID.E. 



Dr. J. C. Mitchell obtained others, measuring 270 to 345 millimetres, in the Lower 

 Nile, near Damietta, in 1895. In the largest of these specimens the external gill 

 measures 20 millimetres. 



Several of the specimens collected by Mr. Loat bore, especially in the axil of the 

 pectoral fin and at the base of the anal, parasitic Copepods, which my colleague 

 Dr. Caiman has kindly determined for me as a species of Lernwocera, probably 

 undescribed. Similar parasites, apparently belonging to the same species, were also 

 found on P. endlicheri, P. senegalus, and on Tanganyika specimens of P. congicus 

 brought home by Dr. Cunnington. 



Called " Abu sheer " or " Abu bisheer " [^ ^1) in Egypt : the first name being the one 

 more often used ; " aU sheer " at Omdurman, the name being applied also to the two 

 other species of the same genus. 



The late Mr. N. R. Harrington, when stationed on the Damietta Nile in June- 

 September, 1898, with the object of elucidating the breeding-habits of Polypterus, 

 obtained between Mansurah and Damietta large numbers of specimens of this species 

 (12 males and 58 females), some laden with eggs, others having evidently spawned 

 quite recently. He has published a paper on their habits*, from which the following 

 notes are extracted : — 



It lives in the deeper depressions of the muddy river-bed, but it is an active 

 swimmer and not essentially a bottom-liver or a mud-fish. It is most active at night- 

 time when in search of its food, consisting mainly of Fishes — Silurids, Eels, Tilapia, 

 Cyprinodon, &c, — which it apparently catches alive, for it prefers live bait and always 

 swallows its food whole. Peculiar in the swimming-movements of Polypterus is the 

 manner in which the head moves freely from the side ; this produces the appearance 

 of a progression more or less snake-like or eel-like, although in general the powerful 

 sweeps of the strong tail characterize the progression as fish-like. The pectoral fins 

 were never observed to be used otherwise than are the pectoral fins of most other 

 fishes, i. e. primarily as balancing-organs, but partly as organs of progression ; the 

 spreading fin-rays give a mobility to the pectorals which is strikingly and beautifully 

 displayed in a high development of the "trembling movement," so often seen in the 

 balancing-fins of Teleosts. The long dorsal fin is not always erect when the animal is 

 swimming ; it can be raised or lowered at will. 



In spite of repeated observations, there is little positive evidence that Polypterus 

 comes often to the surface to breathe. The fish cannot live in brackish water, even a 

 slight salinity kills it. 



The males are smaller than the females and much less numerous; they are 

 generally taken in company with one or more females. 



The time of the breeding can be approximately determined not only by the gradual 



* Atner. Natural, xxxiii. 1899, p. 721. 



