126 iV.K. J. S. BUDGETT ON THE 



of the problem as to what is the function of these fringes in Lepidosiren, it is natural 

 to look to see in what the liabits of the latter differ from those of Profoptej-ns. 



The most striking difference is surely that, whereas Lepidosiren makes its nest 

 several feet below the surface of the ^ater, Protopterus makes its nest practically out 

 of the water. I regard the habit of Frotopteras of lashing the surface of the water 

 at the entrance to its nest as a means of aerating the eggs in the nest. Now, it is 

 tempting to regard the vascular fringes on the pelvic limbs of Lepidosiren as in some 

 way connected with the aeration of the eggs, for it is obviously unable to make use of 

 this method of aeration adopted by Frotoptervs. But the conditions under which this 

 habit was observed in Protopterus were, as I have said, somewhat unusual, in that, 

 owing to prolonged drought, the water in the nest was unconnected with the surround- 

 ing water. When this was not the case, the lashing of the tail on the surface of the 

 water was not observed. Therefore I do not think this habit can be said to be quite 

 characteristic of Protopteriis. The entrances to the nests, however, were always only 

 a few inches at most below the surface of the water, while with Lepidosiren the nests 

 are made in deep water, and it seems more probable that the fringes on the pelvic 

 limbs of Lepidosiren are, as Kerr holds, accessory organs of respiration avoiding the 

 necessity of frequent absence from the nest in order to visit the surface for air, and 

 thus perhaps risking loss of the entrance to the nest or the attacks of enemies. 

 Protopterus, by reason of the_ shalloAvness of the water about the entrance to the 

 nest, would not run these risks in seeking air, and therefore has no need of the 

 accessory breathing-apparatus. 



IV. — The Nesting-habits of Gymnaechus. 



While hunting for Polypterus eggs, I met with several large floating nests measuring 

 in all two feet in length and one in breadth. The nests were made in the dense 

 grasses of the swamp in three to four feet of water (text-fig. 20). The inside measurement 

 was about a foot by six inches. Three sides of the nest projected from the water ; the 

 foiu'th side was several inches lower, being about two inches below surface. The 

 deepest part of the nest was opposite to that side where the wall was low, the bottom 

 being about six inches below the surface of the water. 



In this nest were deposited about a thousand large spherical amber-like eggs 10 mm. 

 in diameter. The eggs hatched five days after being laid, and in eighteen days a 

 thousand young fry of Gymnarchus niloticus left the nest when three inches long. 

 This fish is called by the natives the " Suyo." 



Though there are many interesting features in the development of these eggs, I do 

 not intend to deal with them in detail here, but merely to mention that the develop- 

 ment is exceedingly shark-like. The larvae soon after hatching develop extremely 

 long gill-filaments, which hang down in two blood-red branches from the gill-arches, of 

 which there are four. The yolk-sac, at first spherical, later becomes drawn out into a 



