Bull. U. S. B. F., 1921-22. (Doc. 922.) 



L 



CYC 



M 



-K 



-ABY 

  -EPIC 



-BijG 



--Br 



147 



Photomicrograph of a cross section taken through mid-body region of a i-year-old mussel. Fixed in 

 Gilson fluid and stained with Delafield hematoxylin. X 14.4. ABV, afferent branchial vein; Br, gills; 

 ByG, byssus gland; CVC, cerebro- visceral commi^tm; EPIC, external plicate canals; K, kidney; L, liver; 

 M, mantle filled with genital fulliclcs. 



