11 



On the Generative Processes op the Oyster, Mussel, 



and Cockle.* 



By Daniel Moore, M.D. 



{Read Oct. 23, 1874.) 



The three common edible shell fish — the cockle, mussel, and 

 oyster — belong, as you know, to the Lamellibranchiate Mollusca. 

 The general anatomy of this class I do not intend to touch upon, 

 and the special anatomy only in so far as the generative glands of 

 the three I have named is concerned, feeling sure that you must all 

 be more or less familiar with these creatures. I think I cannot do 

 better in introducing the special subject I wish to draw your 

 attention to to-night than by quoting a passage from the second 

 edition of Professor Owen's " Lectures on the Comparative 

 Anatomy and Physiology of the Invertebrate Animals," published 

 in 1855. In p. 522 he says: — " The latest and best observations 

 of naturalists and physiologists on the sexual characters and 

 generation of the Lamellibranchs have established the correctness 

 of Leuwenhoek's original conclusion, that these mollusks are of 

 distinct sexes, some individuals being male and others female. 

 In the small species of Anarnia, parasitic upon fuci on the south 

 coast of England, I have found the males and females nearly equal 

 in number, the males being distinguished by their opaque white 

 testis abounding in spermatozoa, the females by their yellow or 

 .orange-coloured ovarium." I would contrast with this, the statement 

 on the subject found in Professor Eolleston's " Forms of Animal 

 Life," published in 1870, Int. p. xcvii. He says : — " The 

 Lamellibranchiata are, with a few exceptions, such as Ostrea and 

 Cyclas, dioecious. There is no sexual congress in this class ; 

 the spermatozoa find their way to the ova either in the circumam- 



* The Publication Committee, in printing the above paper, do not commit 

 themselves to the opinions advanced in it, which are much disputed. At the 

 same time they are desirous of drawing the attention of the members of the 

 Club to what they deem a thoughtful and carefully considered paper upon a 

 subject of great interest to Microscopists. 



