226 Proceedings of the 



I. Observations on British Zoophytes. By T. Strethill Wright, M.D., 

 Fellow of the Royal College of Physicians, Edinburgh. 



Description of Plates XI. & XII. 

 Clava. 

 Fig. 1. Corallum and polyps of Clava repens (magnified three diameters). 



2. Clava membranacea (natural size). 



3. Corallum or poly pidom of Clava membranacea after removal of polyps 



by maceration (enlarged). 



4. Portion of corallum of Clava cornea (from Professor Goodsir's speci- 



men ; enlarged). 



5. Diagram of reproductive capsules or polyps on female polypary of 



Clava — a ectoderm — c endoderm — ac generative cavity — d nutri- 

 tive cavity of pedicle and capsules — e ova changing to (/) ciliated 

 planarioid larvae. 



6. Free swimming larvae. 



7. Reproductive capsule of female Coryne glandulosa, lettered as fig. 5, 



and showing the origin of the ova (c) from the external surface of 

 the endoderm. 



Eudendrium. 



8. Eudendrium pusillum with Medusa-buds (eight diameters). 



9. Medusoid of do., with tentacles relaxed. 



11 & 12. Ideal figure of Hydractinia as a Gymnopthalmatous Medusa, and 

 figure of ideal Gymnopthalmatous Medusa — a alimentary — b re- 

 productive — and c tentacular organs or polyps — d visual, and e au- 

 ditory organs. 



13. Gemmation of Medusa from alimentary polyp. 



14. Do. from reproductive polyp. 



15. Do. from tentacular polyp. 



16. Eudendrium sessile, with Medusa-buds (eight diameters). 



17. Single polyp of do. 



On Clava. 

 1. The genus Clava has been hitherto defined by writers on 

 systematic Zoophytology as a single but gregarious polyp, 

 destitute of a polypidom or corallum. Pallas, who, according 

 to Johnston, first described this animal, writes, " Etiam hsec 

 Tubulariis adnumerari debent Zoophytae, quamvis ne quidem 

 ramescent ut Coryne, et tubulo corneo plane destituta sint." 

 Van Beneden remarks, " The individuals are not united to each 

 other," " at least I have not seen, as in Hydractinia, a common 

 substance which unites all the individuals." Johnston, mak- 

 ing no mention of a corallum, says that the polyps are " single," 

 and " fixed by a narrow disc." And the latest writer, Gosse, 

 in his " Manual of Marine Zoology," states that the polyps are 



