d. moore, m.d., on Bucephalus Haimeanus, &c. 51 



for that opinion, beyond such as might be gathered from the plate 

 itself, hoping that, if a discussion bad followed my paper, some 

 facts might have been elicited in relation to them. I found shortly 

 after that the organism I hal figured as the young of the Cockle 

 had been very fully described by M. Lacaze-Duthiers, in the 

 " French Annals of Natural History" (4th series, vol. 1), under 

 the name of Bucephalus Haimeanus, and although the organism I 

 figured as the young of the Marine Mussel has, as far as I know, 

 never been named, it is evidently closely allied to Bucephalus 

 Haimeanus, and, in all essential particulars, has the same life 

 history as far as I have observed. When I promised to give a 

 paper on these two organisms, I intended to bring before you 

 previous observations and conclusions in reference to them, but 

 since the Secretary of " Tbe Royal Microscopical Society" has 

 in their Journal for the current month given an able resume of the 

 subject, I feel it would be merely wasting time to go over the 

 same ground. It will suffice here to say that M. Lacaze-Duthiers 

 considers B. Haimeanus the cercarian form of some unknown 

 Distoma, and describes the tubular structure in which it is found 

 as a collection of sporocysts or nurses which he mentions as 

 filling tbe abdominal glands of oysters and cockles, and rendering 

 them sterile, his opinion being based on the likeness of this 

 organism to the B. polymorphus, described by Von Baer, sup- 

 ported by his own observations, last autumn. M. A. Giard 

 announced, in a note to the Comptes Rendus, a translation of 

 which appeared in the December number of " The Royal Micro- 

 scopical Journal," that he had discovered this organism encysted 

 in the common Garfish, Belone vulgaris, which, as you know, 

 visits our shores annually, and in some parts is known as the 

 mackerel guide. I have no intention, gentlemen, of disputing 

 these statements ; efficient observers consider them facts, and I 

 am thankful for the light they bring. My experience, however, 

 of these organisms has been somewhat different, and as I wish, as 

 far as possible, to avoid giving a controversial tone to my paper, I 

 think it best merely to relate in detail the reasons which led me 

 to a different conclusion, feeling sure that arguments about 

 opinions tend rather to confirm in error, if a mistake has been 

 made, than to settle a question which requires for its elucidation 

 fresh facts or confirmation of facts already recorded. And it is 

 my hope to induce members of the Quekett to examine the subject 



