56 d. moore, h.d., on Bucephalus Haimcanus 



instead of ending abruptly in the general structure, are here 

 attached to a large lamellar portion with its striation running in a 

 different direction. The diagram explains this better than any 

 description can; beyond, it exhibits a triangular marking when, 

 seen directly in front, bnt when seen sideways, the appearance is 

 as shown in the diagram, and which I have thought indicated the 

 presence of rudimentary shells of a more defined character than 

 in B. Haimeanus. The integuments of both these organisms are 

 finely striated. The only trace of internal structure I have 

 detected is an oesophagus leading from the mouth, and which I 

 thought passed through the central organ. In early stages two 

 vacuoles are generally seen, one at the oral, and the other at the 

 lamellar extremity, and a much larger one I have often seen in the 

 centre, which, however, as it is not invariable, may have been 

 accidently produced. The general contents appear cellular, with 

 only slight differences as to size and colour, when the organism has 

 reached the most perfect stage at which I have seen it. I have 

 now come to the end of all I need at present say about these 

 organisms, and I will only add that if B. Haimeanus has been 

 found in the oyster, the interpretation I was led to put on the facts 

 observed must be wrong. The statement that it is so found has, 

 as far as I know, never been confirmed, although it has been 

 repeated. It is contrary to my experience of English oysters, a 

 large number of which I have examined. I need not mention the 

 supposed encystment further than to say, that if it is confirmed in 

 the future, we should be introduced to a life history of a re- 

 markable character, and of great interest. That the ova pro- 

 duced by the perfect Trematode, presumed to develop its sexual 

 character in some voracious devourer of the common Garfish, 

 should be so abundantly deposited on our coasts as to supply 

 cockles with sporocysts, in the number we find them, is such a 

 wonderful phenomenon that we may well hesitate before at once 

 accepting it as fact, seeing that at present nothing is known of the 

 life-history of this supposed fluke, beyond the recorded presence of 

 its sporocysts in certain molluscs, and the encystment of its 

 cercarian form in the Garfish. How the eggs enter the cockle, 

 and then follow their life-history, has not as yet been indicated, 

 and, indeed, nothing is known as to the origin of the structure 

 containing these organisms in the cockle if this hypothesis be 



