Dr. Johnston's Catalogue of Zoophytes. 213 



12. Thuiaria. Polypidora branched, continuous ; stem naked of cells, which are depressed 

 and disposed in two or more rows on the dichotomous branchlets. Ovaries vesicular. 



** Polypidom calcareous. 



13. Cellaria. Polypidom slender, branched, jointed, celleferous throughout ; cells sessile, 

 in rows, united or single. Ovaries vesicular. 



Ord. 5. CELLULIFERA. 



Char, Polypidom fixed, membranous or calcareous, tvitkout any central medulla ; polypes 

 aggregate (not compound), in distinct cells imperforate at the base. 



* Polypidom membranous. 



14. Flustra. Polypidom leaf-like or encrusting; cells contiguous, arranged in regular 

 rows, forming mat-like expansions. 



** Polypidom calcareous. 



15. Faroimia. Polypidom erect, dichotomously branched, constricted at distant intervals; 

 joints tubular ; cells diverging from the axis, immersed. 



16. Cellepora. Polypidom of various forms, encrusting or erect; cells agglomerated, 

 urceolate, the mouths exserted. 



17. Berenicea. Polypidom crust-like, adherent throughout ; cells contiguous, oblique, ar- 

 ranged in regular rows, the mouth at the distal extremity. 



18. Tubulipora. Polypidom branched or simple ; cells rising from the base, long, tubu- 

 lar, cylindrical. 



Ord. 6. APOLYPA. 



Char. Polypidom destitute of polype cells or polypes. 



* Soft and fibrous. 



19. Halichondria. Porous, spongy, of various forms ; the fibrous skeleton strengthened 

 by siliceous spicula. 



20. Grantia. Porous, spongy, of various forms ; the fibrous skeleton strengthened by cal- 

 careous spicula. 



** Hard and calcareous. 



21. Millepora. Irregular, dilated, calcareous throughout, the surface perforated with 

 minute perpendicular pores scattered irregularly. 



22. Corallina. Fixed, plant-like, very much branched, jointed, solid ; the axis continuous, 

 corneous. 



I. Z. CARNOSA. 



1. ACTINIA. 



* Tentacula retractile. 

 I. A. equina, body conoidical liver-brown, or olivaceous, smooth ; tentacula numerous, 



