PLATE X. 



Pig. 



1. A very young Phjsalia, with only a single polypite and tentacle. 



2. A somewhat older specimen. 



3. Opening of the pneumatocyst in a young specimen. 



4. A polypite. 



5 — 7. Various views of villi. 



8. Some of the elevations which cover the outer surface of the lip of the polypite. 



9, 10. Young polypites. 



1 1 . A tentacle, with its basal sac. 



11a. Part of the proximal end of that tentacle ; 1 1 i^, a young tentacle. 



12. A portion of the distal moiety of this tentacle, exhibiting the reniform enlargements ; 



12 a, 12 1^, the thread-cells contained in them. 



13. One of the " velvety processes" magnified. 



13 a. A similar process of the natural size; and 13 i, somewhat magnified. 



14 a — d. Successive stages of the androphore ; 14 e, )'oung spermatic elements. 



15 a — e. Successive stages of the gynophores. 



