PLATE XXIII 



Fig. i . Young stage of development of a genital tuft of a gonodendron 

 of the Plymouth specimen, x 55. 



Fig. 2. Part of an immature male gonodendron, middle stage of de- 

 velopment of an end-branchlet, showing its origin as a sub-terminal 

 bud growing out opposite a jelly-polyp of a terminal palpon. The 

 terminal section on the left (jelly-polyp and palpon) has not 

 developed a sub-terminal pro-bud, which might have given rise to 

 a pair of similar end-branchlets. x 40. 



Fig. 3. Part of an immature gonodendron of the Plymouth specimen. 

 Passing from below round to the top right three typical end- 

 branchlets at an early stage of development can be seen. Each 

 consists of a terminal section (appearing to be basal and consisting 

 of jelly-polyp and terminal palpon) and a sub-terminal section (top 

 right) consisting of nectophore and sub-terminal palpon. Rudi- 

 ments of gonophores are visible. One gonophore always appears 

 at the base of the terminal palpon. x 55. 



Fig. 4. Part of the ectoderm of a female gonophore freed from the 

 endoderm and the covering exumbrella of the medusoid, to show 

 the sinuous band of oogonia. x 15, further magnified on the right. 



Fig. 5. Fully grown male gonophores. Inside the thin outer mem- 

 branes can be seen the cap of spermatocytes, completely sur- 

 rounding the spadix. x 17. 



Fig. 6. Part of a female gonodendron from specimen Lanzarote, no. 25, 

 dropped in the laboratory, to show the endoderm of the gono- 

 phores drawn inside out into the lumen of the branch of the gono- 

 dendron. x 15. 



