DESCRIPTION OF PLATES. Xlll 



3. Siphonactiuia (Peacliia) hastata, p. 174. 



4. Iljantlius scotticus (after Forbes), p. 173. 



5. Polythoa arenacea (Z. Couchii), after Couch, p. 182. 



6. Caryophyllia Smithii (after Gosse), p. 184. 



Plate XV. 



1. Polyp of Alcyouiuni digitatum, enlarged, p. 195. 



2. Section tlirougli polyp of A. digitatum (after Hert- 



wig), p. 191. 



3. Pennatula pliosphorea (after Milnes-Marshall), p. 



197. 



4. Virgularia mirabilis (after Milnes-Marsliall), p. 199. 



5. Gorgonia verrucosa (after Couch), p. 1,96. 



Plate XVI. 

 Diagrams descrij^tive of structure of Polyzoa. 



1. Diagram of Polyzoa (after Busk). 



2. Diagram of Bowerbankia (after Hincks). 



3. Polyzoon with polypide retracted (after Hincks). 



4. 5. Communication plates (after Hincks). 



6. Alimentary canal of Cellepora (after Hincks). 



7. " Bird's Head " processes, p. 208. 



8. Structure of Notamia bursaria (after Busk). 



For descriptions of these figures, see chapter on 

 Structure of Polyzoa, pp. 201 — 210. 



Plate XVII. 



1. yEtea anguiua, nat. size. 1a, Enlarged, p. 212. 



2. Eucratea chelata, enlarged, p. 215. 



3. Gemellaria loricata, nat. size. 3a, Enlarged, p. 217. 



