ECHINODERMATA OF NEW ENGLAND. 29 



Athecata. 1 

 Without thecae for hydranth or sexual bodies. 



A. Forming calcareous encrustations. . Hydractinia. 



B. Erect, plant-like, not parasitic. 



I. Solitary. 



a. Tentacles capitate, scattered over the 



body Acaulis. 



b. Tentacles filiform, in two circles. 



Corymorpha. 



II. Associated. 



a. Tentacles of one kind. 



Tentacles capitate in single whorl. 



Clavatelia. 

 Tentacles filiform. 



a. Two separate rings of tentacles 



with free medusae. Ectopleura. 



b. Two tentacular circles without 



medusas . . . Tubularia. 



c. Scattered, with hydranth on branch 



of stem .... Tubiclava. 



b. Tentacles in single verticil, without 



bosses. 



Polyps sessile . . . Podocoryne. 

 Polyps on stem, with trumpet-shaped 

 proboscis .... Eudendrium. 

 Hydranth without covering, Avith coni- 

 cal proboscis. Gonophores on ccen- 

 osarc. 



a. Arborescent . . Bougainvillia. 



b. Small, simple habit. 



Perigonemus. 



>Thc,*or;cnpS surrounding the hydranth or stomach with a crown of tentacles 

 about a mouth. Athecata; a, 0>jKa, without a cup. Thecaphora; 0rjKa-<f>e'pw, cup 

 bearing. 



