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



213 



212 



214 



215 



Crosssections through the mantles of mussels collected a t Weeds Hole. Mass. All figures arc photomicrographs of 



material fixed in Gilson fluid and stained with Delafield hematoxylin and congo red. X 30- 

 Fig. 212. — Fromafemalemussel collected on December 1. 

 Fig. 213. — From a male mussel collected on December 1. 

 Fig. 214.— From a female mussel collected on June 16. 

 Fig. 215. — From a male mussel collected on June 16. 



