DEVELOPMENT OF THE OYSTER. 



Explanation of Plate XLII. 



Figure 67. Section of a portion of the visceral mass of a male oyster magnified 250 diameters. The surface- 

 epithelium of the body is shown at the lower end of the figure. Above this is a loose, thick layer of wriuliled cells, 

 which have the appearance of adipose cells from which all the fat has been removed. Above this layer is a large 

 duct, lined with epithelial cells, and filled with ripe spermatozoa, which have been poured Into it from two follicles, 

 which communicate with it on each side. Above this are sections of a number of the follicles of the testis, in three 

 of which the contents are figured. 



