ECHINODERMATA OF NEW ENGLAND. 33 



A. 



Hydractinia. Clavate sessile filiform tentacles from a 

 conical proboscis from the ccenosarc. Naked polypary. 

 Some polypites are partially developed and bear spheri- 

 cal clusters of thread cells. No medusae. Found on shell 

 inhabited by Eupagurus, or on floating wood, spiles, etc. 



H. echinata. 



B. 



Acaulis. Solitary, cylindrical, terminated above in a 

 conical proboscis. Adherent. Tentacles scattered, small 

 over whole body. Gonophores clustered about base. 



A. primarius. 



Corymovplta. Polypite solitary, in delicate sheath. 



Two sets of filiform tentacles. Oral tentacles in several 



verticils placed close together. Prominent proboscis. 



Roots attached in sand. 



G. nutans. 



Ectojpleura. Stem delicate, slightly branched. Twenty- 

 four oral ; thirty lower tentacles. Medusae developed be- 

 tween the two series. 



E. ochracea. 



B. II. b. 



Tubularia. Stem simple and branched, rooted by a fil- 

 iform stolon with inverted polypary. Filiform tentacles 

 in two whorls. Gonophores on peduncles between two 

 whorls of tentacles. Young has an actinula form. 



T. indivisa. 



Clava. Clavate, tentacles smooth, sheathed in chiti- 

 nous polypary. Buds borne in clusters. No medusae. On 

 Fucus. 



C. leptosiyla. 



Tubiclava. Erect stem with branches and creeping 



ESSEX INST. BULLETIN, VOL. XXm. 3 



