FLOATING EGGS 135 



namely, the Indian murral, Ophiocephalus striatus? 

 as compared with the American bowfin, Amia 

 calva, species which are far enough apart in the 

 systematic scale, the former a Teleostean, the 

 latter a Ganoid. Both make circular clearings 

 in the shallow water of lakes or irrigation tanks, 

 biting away the surrounding weeds ; and in both 

 cases the male parent tends the nest, lying in 

 wait in special runways. But whereas the eggs 

 of Amia are strewn over the bottom of the nest, 

 those of the murral float in a single layer at 

 the surface, in contact with one another, but not 

 adhering together. This exceptional behaviour 

 of the eggs of a fresh-water fish is shared by 

 those of another species of the same genus, 

 Ophiocephalus punctatus. 



These floating eggs of Ophiocephalus owe their 

 buoyancy to the presence of a single large oil- 

 globule, which occupies the greater part of the 

 bulk of the ovum and is immersed in the amber- 

 coloured yolk adjacent to the uppermost pole 

 of the egg. The eggs thus come to lie immedi- 

 ately below the surface film of water, exposed 

 to the quickening influence of air and sun, and 

 protected thereby from the attacks of fungi, to 

 which they are extremely liable as soon as 

 the conditions of existence fall below a certain 



1 A. Willey, " Observations on the Nests, Eggs, and Larvae of 

 0. striates," Sfiolia Zeylanica, vol. vi., 1909; (1910), pp. 108-123. 

 The comparison with Amia is based on the description given by 

 Professor Bashford Dean. 



