462 ON THE CHEILOSTOME POLVZOA 



reddish coloration ; but in those still further advanced, a similar, but 

 larger and redder, body makes its appearance in the ovicell, and after 

 undergoing yelk-division becomes a ciliated embryo. In these older 

 cells, again, we find the granular mass at the bottom of the cell 

 gradually developing into a mass of spermatozoa, which eventually 

 float loose in the cavity of the cell. 



I have no doubt, therefore, that in Bitgida avicularis the ovarium 

 is situated at the top of the funiculus, the testis at its base ; that 

 impregnation takes place in the cavity of the cell, and that the ovum 

 passes from thence into the ovicell — there, as in a marsupial pouch, to 

 undergo its further development. The testis has a similar form and 

 structure, and its position is invariably at the bottom of the cell in 

 Bngiila flabellata, B. plumosa, and Scnipocellaria scniposa, but that 

 of the ovarium varies greatly. Thus in B. flabellata the ovarium is 

 placed at the middle of the back of the cell, and is not directly con- 

 nected with the funiculus ; in B. plumosa, it lies at the apex of the 

 back of the cell ; in Scritpocellaria scruposa, it is at the upper and back 

 part of the cell. The ovarium rarely presents more than one or two 

 ova. 



