PLATE 33.— Polypi (Zoophytes). 



Figure 



1 . Areolar tissue of sea-anemone (^Actinia mesembryanthemum) ; with spicula, 



cells, and fibre-cells. 



2. Spicula from the same. 



3. Alcyonella sfagnorum. a, entire polypidom ; b, perpendicular section, showing 



tubes and ova ; c, back view of polype with tentacles ; d, ova. 



4. Campamdaria volubilis. a, growing upon a piece of Plwmdaria fahata ; 



b, portion of polypidom more magnified ; 4 c, cell of Laoniedea dichotoma 

 with ova. 



5. Portion of polypidom of Cellidaria reptans. 5 «, Cellularia ciliata ; 5 b, the 



same more magnified, * a bird's-head process ; 5 c, posterior view of a cell of 

 Cellularia reptans, with its appendices ; 5 d, three appendices to a cell of the 

 same ; 5 e, polype expanded. 



6. Cor allium rubrum ; axis with polypiferous crust. 



7. Spicula from the crust. 



8. a. Transverse section of the axis of red coral, from the furrowed exterior towards 



the centre ; b, longitudinal section. 



9. Polype of Cristatella mucedo. 



10. Ova of the same, seen from above. 



1 1 . Branch of Sertularia rugosa. 



12. Portion of the same, magnified, with cells a, and vesicles b. 



13. Set'tidaria pmnila. 



14. Portion of the same, magnified, a, cell; b, vesicle. 



15. Sertidaria operculata. 



16. Portion of the same, magnified, a, cells; b, vesicles. 



17. Lepralia variolosa. 



18. Membranipora pilosa, with polypes protruding from the cells. 18 c, single 



polype ; a, cell ; b, valve through which the ciliated tentacles c protrude ; 

 d, oesophagus ; e, pouch containing the stomach, liver, &c. ;f, place of gyration 

 of particles in intestine ; g, rectum. 



19. Viece of Flustra carbasea. 



20. Cells of the same, magnified. 



21. Hydra viridis, attached to Lemna. 



22. Stinging organs of Hydra vulgaris. «, capsule with the spines and filament 



enclosed ; b, capsule with the spines and filament protruded ; c, very minute 

 capsules ; d, capsule imbedded in a globule of the sarcodic substance of the 

 body. 



23. Tentacle of Hydra viridis, a, stinging organs in situ. 



24. Hydra viridis, with spermatic capsules a, and ovarian capsule b. 



25. Ovum oi Hydra, with the young polype bursting through its shell. 



26. Bird's-head processes of -F/zd5^?-« «t'/c?«/«;'i>. \ 



27. Spicula of a G^or^o?i2a. ' 



28. Spicula oi Alcyonium digitatum. 



29. Globules of sarcodic substance of a crushed Hydra viridis. a, one containing a 



small vacuole and several green granules ; the latter are more magnified below; 

 b, a globule greatly distended by the formation of a large vacuole. 



30. Tubulipora, with a polype protruding from a cell. 



