No. I.] EMBRYOLOGY OF THE ISOPOD CRUSTACEA. 6^ 



I believe that the chitinous capsule is a portion of a sper- 

 matophore which is deposited upon or inserted into the dor- 

 sal surface of the female, passing downwards and backwards 

 to reach the oviduct just where it joins the ovary. I have not 

 investigated the structure of the spermatophore in detail, nor 

 have I observed the manner of its formation by the male, but 

 believe that the evidence I have gathered warrants the inter- 

 pretation here given. In one set of sections the capsule lay 

 just beneath the hypodermis in the fifth thoracic segment, and 

 extending backwards from it was a tube formed of a single 

 layer of cells, and containing a granular mass which did not 

 take a carmine stain. This I take to be the body of the sper- 

 matophore undergoing degeneration, the spermatozoa which it 

 originally contained being found in the oviduct and especially 

 in a dilated portion of it near its proximal end, which may be 

 termed the receptaculum seminis. Fertilization takes place 

 apparently in the oviduct ; 

 at all events I have not 

 found spermatozoa in the 

 ovary, though it is possible v S-^y.'--- ! ?' ^^ 

 that they may pass into it 

 during the moult which ov rs od 



precedes OVipOsition, a S Relationships of the Various Parts. 



they are stated to do in 



Porcellio and other land-forms by Friedrich ('83). The rela- 

 tionships of the various parts concerned are represented in the 

 diagram above. 



The varying position of the chitinous capsules is to be ex- 

 plained as stages in their expulsion from the body after the 

 spermatophores have discharged their contents. They appear 

 to migrate down the canals originally occupied by the bodies 

 of the spermatophores, these latter seeming to degenerate, and 

 later they reach the oviducts, passing to the exterior finally by 

 these. At least I have found them in sections close to the 

 proximal ends of the oviducts, and also lying in the oviducts 

 just internal to their external opening. I could not find any 

 trace of the bodies of the spermatophores when the capsules 

 had reached the oviducts, and, furthermore, the canals extend- 



