21 



Fig'. 12. Two eiulodormal myo-epitlielial cells. 



Fig. 13. Section tliioiigli an ovum earlv in December, 

 showing tlie large germinal vesicle close to the 

 periphery and the single large germinal spot 

 which it contains. 



Fig. 14. Section through a spermary in the autumn, 

 showing the endodermal capsule which covers 

 it, the central (bl.) protoplasmic mass (blasto- 

 phor) in the centre, and the densely crowded 

 nuclei in the periphery. 



Fig. 15. Diagrammatic vertical section through an 

 anthocodia. >S'/. the sij^honoglyph on the 

 ventral side of the stomodaeum. V^mf. a 

 ventral mesenterial filament. 3fsf. a ventral 

 mesentery. R.M.sc. retractor muscle. 7\ 

 tentacle. Go)i. Gronad, and the other letter- 

 ings as in Fig. (J. 



Plate III. 



Figs. IG, IT, 18. Three stages in. the development of 

 Alcyonium, as seen in transverse section. 

 Fig. 16, the morula stage of eight cells, the 

 nuclei of three of these cells can he seen in a 

 star-shaped island of clear protoplasm, the 

 remainder of each cell is filled with closely 

 crowded globules of yolk, which are not 

 represented in the drawing. Fig. IT. A later 

 stage in which a space has appeared in the 

 centre of the embryo, but the cells are still 

 undifferentiated. Fig. 18. A planula stage, in 

 which the archenteric space is much larger, 

 the ectoderm is fully differentiated and 

 ciliated, and the endoderni a continuous 



