52 THE OYSTER. 



PLATE IV. 



THE DEVELOPMENT OF THE OYSTER. 



All the figures are highly magnified and all except 



Figure lO are autograph reproductions from the 



author's drawings from nature. Figure lO is copied 



from a figure by R. T. Jackson in the American 



Naturalist, December, 1890. 



Figure i. A newly laid ^^^ with the male cells 

 fastened to its surface. 



Figure 2. Oyster embryo, about two and a half 

 hours old. 



Figure 3. An embryo about fifteen minutes older 

 than Figure 2. 



Figure 4. An embryo about fifteen minutes older 

 than Figure 3. 



Figure 5. An embryo about twenty minutes older 

 than Figure 4. 



Figure 6. An embryo about thirty hours old, at 

 the beginning of the swimming stage. 



Figure 7. Stage in which the first traces of the shell 

 make their appearance. 



Figure 8. A swimming oyster about three days 

 old. 



Figure 9. A swimming oyster about six days old. 



Figure id. An oyster which has become attached. 



