Introduction
In a previous paper (Biological Bulletin, vol. 34, no. 5, May, 1918) I traced the spermatogenesis of the edible crab of the Pacific coast, Cancer magister Dana. I n the present article various stages in the spermatogenesis of three other species of Cancer crabs, namely, Cancer productus Randall, Cancer oregonensis (Dana) Rathbun, and Cancer gracilis Dana, will be discussed from a comparative standpoint. These forms, like Cancer magister, are also common t o the Pacific coast of the United States, being quite abundant along Puget Sound, where most of the material f o r the present research was obtained.
Methods
The testes studied are constructed on the same plan as those described by Binford ( '13) and myself (Fasten, '15, '18) f o r various Brachyura. By referring to my previous publications (Fasten, '15, '18) , figures and descriptions of these male gonads may be obtained. Smear preparations prepared during the latter weeks of June and the early part of July were used exclusively for the present studies. I have found this period to offer the best material for the study of the spermatogenesis stages of the various Cancer crabs under consideration.
While sectioned material was also available, the smear preparations were found to give such superior results that 47