32 BHITISJr ITYDROID ZOOPHYTES. 



TABLE C. 



Sj'Htematic Table to show the position of the 



HYDEOMEDUS^ (CRASPEDOTA) 



(Hydroids, Hydrozoa, and Hydroida, of various Authors) 



in the classification of the CCELENTERATA. 



Phylum CCELENTERATA. 



Radially symmetrical animals with only one cavity in the body 

 — the gastrovascular space — which serves alike for digestion and 

 circulation. The generative cella are always either ectodermal 

 or endodeiTnal. 



Sub-phylum I. CNIDAKIA 



Coelenterata with thread-cells. 



Class I. HVDROMEDUSiE (CRASPEDOTA). 

 Cnidaria in which the medusa has a velum and the polyp is 

 without gastral ridges or filaments. 



Order 1. HYDRIDA. 

 Solitary polj'ps without medasoid buds. Both generative 

 products are developed in the ectoderm of the polyp. 



Order 2. HYDROCORALLIN^. 

 Colonial Hydromedusae, consisting of a meshwork of coenosarcal 

 canals, the ectoderm of which secretes a hard calcareous matter, 

 filing up the spaces of the meshwork. Polyps of two forms, 

 gastrozooids and dactylozooids. 2 Families. 



Order 3. TUBULARIiE (GYMNOBLASTEA). 

 Without hydothecae and gonangia. Polyps, >\lien more than 

 one, forming permanent colonies. Generative individuals, 

 when set free, are Anthomedusie. 4 Sections. 14 Families. 



ANTHOMKDUS/K. The MedusK of this Order. 



Craspcdota without otiK-ysts. with ocelli at the base of the 

 tentacles, and with manubrial gonads ; radial canals, usually 

 4, rarely 6 or 8 ; budded fvi)m poljT^JS of the Tubulariae. 

 4 Families. 13 Sub-families. 



