No. 393:] HE LIFE HABITS OF POLYPTERUS. 725 
mature fish do not survive salt water long enough even to shed 
their ova. 
2. Place and Time of Breeding. —If the specimens taken 
at Mansourah are not migrating, where and when does Polyp- 
terus breed? Probably at any point on the river where the 
adult fish may be found in numbers. Such regions are pre- 
sumably to be found about the head waters of the Nile, and it 
is possible, further, that, like some other river fishes, they pre- 
fer the small brooks or springs for spawning. There seems to 
be no reason, however, why the few fish, which are found 
heavily laden with eggs at Mansourah, should not spawn in this 
vicinity, z.e., below the first cataract ; for it is practically impos- 
sible for them to pass the barrage. Besides the individuals 
taken with eggs, others were observed, the ovaries of which 
retained only here and there a few large ova still attached, the 
remainder having evidently been cast out. 
The time of the breeding of Polypterus can be approximately 
determined not only by the gradual 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 inun- 
dation of the Nile. Cyprinodon, which brings forth its young 
alive, was one of the earliest fish to spawn, and its eggs had all 
disappeared before the middle of July. Between this time and 
the first of September, Schal, Schilbe, Bayard, and Armoot, in 
the order named, laid their eggs. The latter spawned latest, 
and its eggs during the summer seemed to keep pace in ripen- 
ing with those of Polypterus. 
Copulatory Organ. — The anal fin of the male Polypterus, 
which has already been described as being somewhat larger 
than that of the female, is undoubtedly a copulatory organ. 
When the fish is alive, this fin, if blown upon or irritated, 
assumes a hollow and pointed spoon-shaped appearance. 
List of Fish Taken. — There follows a partial list of the fish 
taken during the summer, with occasional reference to the con- 
dition of the reproductive organs. 
June 10. 7-8 bichir, principally dead females which carried 
large numbers of ova. 
