Bull. U. S. B. F., 1921- 



(Doc. 922.) 



216 



^ 







217 



iMtafevaUMta 



218 





ss 





-• 







..... .. 



213 



220 



Cross sections through the mantles of mussels collected at Woods Hole, Mass. All figures are photomicrographs of 



material fixed in Gilson fluid and stained with Delafleld hematoxylin and Congo red. X 30. 

 Fig. 216. — From a female mussel collected on January 12. 

 Fig. 217. — From a male mussel collected on January 12. 



Fig. 218. — From a female mussel collected on July 16 after spawning had taken plate. 

 Fig. 219. — From a female mussel collected on April 27. 

 Fig. 220. — From a male mussel collected on April 27. 



