CRISIAD^ : CRISTA. 



283 



Milne-Edwards. The Crisiadoe differ from the Tubuliporidse in ex- 

 ternal form only, evolving not in little crusts or wart-like masses, 

 but in neat confervoid tufts of ivory whiteness, which often confer 

 additional beauty to the sea-weeds they infest. The polype is an 

 ascidian of the normal structure, but yet examined in only one or 

 two species. On the polypidom may frequently be seen pear-shaped 

 vesicles of the same texture as the polype-cells, and very like the 

 ovarian vesicles of the Sertularinte, (Fig. 62 and G3,) but that the 

 use of them in the two tribes is the same cannot be said to be yet 

 determined. No other Polyzoan possesses them. 



Fig. 62. 



Fig. 63. 



6. Orisia,* Lamouroux. 



Character. — -CeUs in two roios, suhalternate ; the aperture 

 entire and terminal. Fig. 62. 



1. C. EBURNEA, ''^ cells looseli/ aggregated^ Cylindrical^ bent, 

 tubular^ orifices free r Ellis. 



Plate L. Fig. 8, 4. 



Tufted Ivory Coralline, EUh Corall. 39, no. 6, pi. 21, fig. «, A. — Sertularia eburnea, 

 Lin. Syst. edit. x. 810. Lin. Syst. 1316. Esper Pflanz. Sert. tab. 18, fig. 1-3. 

 Berk. Syn i. 220. Turt. Gmel. iv. 686. Jameson in Warn. Mem. i. 565. Turl. 

 Brit. Faun. 217. Stciu, Elera. ii. 449. — Cellularia eburnea, Fall. Blench. 75- 

 Hogg's Stock, 35. — La Sertolara d'avorio ? Cavol. Pol. Mar. 240, tav. 9, fig. 5, 6. 



From Kpiffic, separation. 



