28 ANTHOZOA HYDROIDA. 



I arrange the British species of this order under the follow- 

 ing tribes, families, and genera : 



* Ovisacs or bulbules naked, bud-like, pullulating from the bases of 



the tentacula. TUBULARINA, Ehrenberg. (Tubularia, Linnaeus. 

 Tubulariadse, Johnston. Les Tubulaires, Van Beneden.) 



Family I. Polypes naked, or with only a rudimentary polypi- 



dom. CORY N ID ^E. 

 t Polypes naked 



The tentacula scattered. CLAVA. 



The tentacula in one row. HYDRACTINIA. 



t t Polypes with a horny cuticle 



The tentacula with globose tips. CORYNE. 



The tentacula filiform. CORDYLOPIIORA. 



Family II. Polypi dom fistular : the tentacula whorled. TU- 



BULARIAD^E. 



t The tentacula in a single whorl. EUDENDRIUM. 

 t t The tentacula in a double whorl 



Polypidom rooted. TUBULARIA. 



Polypidom unrooted and deciduous. CORYMORPHA. 



* * Ovisacs in the form of horny capsules or vesicles scattered on the 



polypidoms and deciduous. SERTULARINA, Ehrenberg. (Sertu- 

 laria, Linnceus.} 



Family III. Cells of the polypes sessile. SERTULARIAD^E. 

 + Cells biserial 



Cells alternate, tubular. HALECIUM. 



Cells vasiform, everted. SERTULARIA. 



Cells conico-tubular, appressed. THUIARIA. 



t t Cells uniserial 



The branchlets plumose or pectinate. PLUMULARIA. 



The branchlets whorled. ANTENNULARIA. 



Family IV Polype-cells on ringed stalks. CAMPANULA- 

 RIADJE. 



Cells alternate, campanulate. LAOMEDEA. 



Cells irregular or whorled. CAMPANULARIA. 



* Polypes propagating by buds and ova, which develop them- 

 selves on and in the body of the parent. HYDRINA, Ehrenberg. 

 (Hydra, Linnaeus. HYDRAIDJ*:, Johnston.) 



One genus only. HYDRA; 



