xi PRACTICAL HINTS FISHES 563 



the Nile, and a fourth to the Niger Delta with the same object in 

 view. The three first expeditious were fruitless but on the fourth 

 he was fortunate enough to obtain ripe males and females and to 

 accomplish fertilization of a number of eggs. Unhappily Budgett did 

 not live to work out this precious material, falling a victim to black- 

 water fever soon after his return to England. The Budgett material 

 has been investigated (Graham Kerr, 1907) but further material is 

 urgently needed to work out much of the detail. 



On the Gambia and on the Upper Nile Budgett found females with 

 eggs in the oviducts during July and August ; in the Niger Delta 

 during August and September. During these periods he found that 

 at any one time only a small proportion of males had active motile 

 spermatozoa in their urinogenital' sinuses so that it looks as if 

 the actual breeding season of each individual male were very short. 

 The fertilizations which were successful were effected with teased- 

 up testis, the tubules being much distended and the sperm clear 

 instead of opaque as it frequently is. In some cases Budgett found 

 that eggs from the splanchnocoele gave a larger percentage of 

 successes than those from the oviduct. 



The fertilized eggs adhered strongly to the bottom of the dish 

 and this supports the statements made by the natives that in 

 nature the eggs are attached to sticks and stems of plants under 

 the water. 



Nothing is known regarding the development of the other 

 surviving Crossopterygian Calamiclithys. 



Of the Actinopterygian ganoids, whose haunts are more accessible 

 and less unhealthy than those of Polypterus, the development has 

 been worked out more or less completely in the case of each of the 

 main types the Sturgeon (Acipenser), the Garpike (Lepidosteus\siud 

 the Bowfin or Dogfish (Amia). 



At the large fishery stations such as those on the Elbe or Delaware 

 Rivers ripe Sturgeons are caught during a brief season on their way 

 into the river to spawn. The eggs and spermatozoa may be obtained 

 by " stripping " the fish i.e. by firm pressure passed backwards along 

 the sides of the body, or by opening the fish. The eggs are im- 

 mediately placed in a dish and a little of the sperm mixed with 

 ;i small volume of water is poured over the eggs, the whole being 

 stirred gently for about ten minutes. They are then distributed in a 

 single layer over the bottom of a submerged shallow tray made with 

 coarse mosquito netting to which the eggs adhere firmly within 

 twenty minutes. The trays are then placed in wooden hatching 

 bdxes with gauze ends and moored in the river so that they are 

 traversed by a constant current. The dark-coloured somewhat 

 tadpole-like larvae hatch out in from three to six days. 



Lepidosteus (Dean, 1895) breeds at Black Lake, N.Y., normally 

 between the middle of May and the middle of June, the eggs being 

 fertilized at the moment of spawning and being distributed over the 

 bottom in shallow water, adhering firmly to stones and other solid 



