ElTCRATIADiE : HIPPOTHOA. 291 



the Vorticellae ; but the conjecture has been shewn to be groundless 

 by Mr. Lister's discovery of its polypes, which are truly ascidian, 

 and nearly allied to those of the Flustra. 



10. HippoTHOA,* Laraouroux. 



Character. — Polypidom confervold^ adherent and creeping^ 

 calcareous^ irregularly hranched^ the branches frequently anas- 

 tomosing^ formed of elliptical cells linked to each other at the 

 extremities ; aperture lateral, near the distal end. — Polypes 

 ascidian. 



1. H. cATENULARiA^ cclls contiguous., ovate, thick, with a 

 large oblique oval aperture. Prof. Jameson. 



Plate L. Fig. 9, 10. 



Tubipora catenularia, Jameson in Wern. Mem. i. 561. — Tubipora catenulata, Ste%i}. 

 Elem. ii. 425. — Hippothoa catenularia, Flem. Brit. Anim. 534. Hassall in Ann. 

 and Mag. Nat. Hist. vi. 170. Couch Zooph. Cornw. 43: Corn. Faun. iii. 10], 

 pi. 18, fig. 5. — Hippothoa EUiotae, Gray Zool. Misc. 34. 



Ifab. On shells, especially bivalves, in deep water, not un- 

 common. 



Polypidom closely adherent, much and irregularly branched in a 

 confervoid manner, white, smooth, glossy, calcareous, the branches 

 spreading, frequently anastomosing, sometimes parallel and coales- 

 cing, formed of a series of cells connected like a string of bugles ; 

 cells oval, widest and rounded anteally, the aperture oval with a 

 plain thickish rim, placed near the top. In its mode of ramifica- 

 tion this coralline resembles many of the plant-like figures in 

 marble or agate. " The branches proceed nearly at right angles, 

 issuing from the margin beside the mouth," and will spread, on a 

 favourable site, to such an extent as will cover an inch or two 

 square surface. When alive it "appears like dew drops, and is 

 easily separated from the shell by a pin ; but is strongly attached 

 when dry." Grai/. In this state the aperture of the cells is some- 

 times closed by a membrane. The polype remains undescribed. 



2. H. divaricata, cells remote, ovate-lanceolate or fusiform, 

 the aperture small and round. Miss Elliott. 



* A Nereid : Hesiod. Theog. 251. 



' iTTTroBoi) t' epoiffcra, Kai 'jTnrovor] pocoTn)xi'C- 

 The charming Hippothoa and rosy-armed Hipponoe. 

 The genus Terebripora of D'Orbigny appears to be synonymous with Hippothoa. 



iJ 2 



