310 ALLEN. 



EXPLANATION OF PLATE I. 



FIGS. 1-7 x 190 ; FIG. 8 x 270. 



FIG. i. Young medusa bud showing the formation of the germinal cells from 

 ectoderm of bud. ec, ectoderm ; en, endoderm ; h, germinal cells. 



FIG. 2. Later stage, germinal cells separated from the ectoderm of the bud. 



FIG. 3. Still later stage showing the mode of formation of the endodermal 

 layer of the bell (/), the inner ectodermal layer (i), and the manubrium (). 



FIG. 4. Showing the layers of the bell completely formed. 



FIG. 5. Distal end of mature female gonophore showing tentacles (/), rudi- 

 mentary radial canals (re), outer ectodermal layer of the bell (ec), and endo- 

 dermal layer (/), inner ectodermal layer (/). 



FIGS. 6, 7. Showing growth of the egg by the absorption of the primitive egg 

 cells (/>). Syncytium thus formed (_y) ; nuclei of absorbed cells (a); young grow- 

 ing cell (e). 



FIG. 8. Longitudinal section through peduncle from female head showing 

 gland cells (G). 



