Bucephalus to the cockle. 63 



with a needle, the eggs, having considerable space available, shifted 

 easily to and fro in the tube. 



The second case was noted on the 14th and 16th. Here there 

 was a tube which gave the impression of having been recently 

 emptied. The Cockle was not very fresh, and may have been 

 delivered in the fresh water in which it had been placed, Bunches 

 of sacs were found in every part ; they were filled with eggs like 

 those just described, and noted as precisely the same as previously 

 seen in the tubes. 23 



The bearing of these cases I shall presently indicate. Mean- 

 while I must revert for a moment to the true character of the 

 ovisacs of the Cockle. I doubt whether they are really com- 

 posed, as Dr. Moore suggests, of two membranous sacs, one within 

 the other ; if so, the outer seems to have disappeared when the 

 eggs have begun to develop ; and differing from him, I suppose 

 the tube to be continuous, at least by its inner layer, not with the 

 outer sac, if such exists, but with that which contains the eggs and 

 answers to the inner sac of Dr. Moore. Some of the characteristics 

 of the sperm sacs and ovisacs make me still doubtful of the 

 hermaphrodism of the Cockle. 



The discovery by Mr. Badcock of some free specimens of 

 B. polymorphus in his aquarium was the means of calling my 

 attention, last December, to existing descriptions of the Bucephalus, 

 and upon these I wish to make a few comments. Of course the 

 existence of Bucephalus in creatures whose own progeny has been 

 traced would settle the question of its parasitic nature ; if, there- 

 fore, the observations of M. Lacaze-Duthiers as to its presence in 

 the Oyster be reliable, the Bucephalus found in our Cockle is a 

 parasite. But, then, as I shall show, some interesting facts disclose 

 themselves; for if the observations made by me are correct, it 

 follows that the statements of M. Lacaze-Duthiers will not alto- 

 gether hold good — at least they will not apply to the Cockles of our 

 harbours. It is certainly curious that, whilst among those of the 

 locality in which my observations are made the Bucephalus is 

 found in so large a proportion, I have never seen it in a single 

 Oyster from the same place. 



With regard to the development of Bucephalus described by 

 Lacaze-Duthiers some differences have been noted by me. He 

 says that from a perfectly transparent spherical globe, without 



2S April 14 and 16, 1875. 



