THE OLAM AND OTBER BIVALVEI) SHELL-FI8E. 69 



We will for a moment look at the life of an oyster. It 

 may be divided into three periods. 1. The fry. In about six 

 hours after life begins the germ swims about in the water, 

 and in a few hours more looks as represented in Fig. 69, i. 



Fig. 69.— 1. Youi^ oyster seen from the side immediately after fixation by the 

 mantle border (m); v, ciliated velum, or paddle; 2, four young European oys- 

 ters taken from the beard of the parent, enlarg^ 96 times ; 6, veiy young spat, 

 showing the peculiar form of the true larvd shell and that of the spat x35 

 times; 7, twenty-days-old spat (natural size); 10, young oyster, 2J^ to 3 

 months old.— After Ryder. 



It now has a minute shell, and swims about, by means 

 of two little flaps, fringed with minute, slender hair-lik« 

 processes called "cilia." It swims near the surface of the 

 ocean, and is borne about by the currents, and it is in this 



