THE 



CANADIAN EECORD 



OF SCIENCE. 



VOL. IX. JULY, 1904. Nos. 3 and 4. 



The Canadian Oyster. 



(Bead before the Natural History Society of Montreal, 

 February 1, 1904.) 



The following paper contains some impressions on 

 the Oyster Fishery of Canada, gained during a six- 

 weeks' sojourn at the Canadian Marine Biological 

 Station at Malpeque, P.E.I., during the summer of 

 1903. The Oyster, as most are aware, belongs to the 

 bivalve section of the Mollusca or shell-fish, and is a 

 relative of the Clam. This division of the Mollusca is 

 usually designated Lamellibranchiata from the lamellar 

 (plate-like) character of the gill. The shell is secreted 

 by a fold of skin hanging down freely at the side of 

 the body, termed the mantle, and the bivalve character 

 of the shell is due to the fact that in Lamellibranchiata 

 the mantle consists of a right and left fold, each of 

 which secretes one valve of the shelF, whilst the flexible 

 horny hinge which unites the two valves is secreted 

 by the skin of the back of the animal, just between the 

 points of origin of the two folds constituting the 

 mantle. 



The Oyster however differs from the Clam and in- 

 deed from most of the Lamellibranchiata in several 

 important respects. As a rule in bivalve Mollusca both 



< valves are precisely similar in size and shape, and the. 



2 animal during life assumes an upright position with 



CQ . 



CL 

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