32 BRITISH HYDROID ZOOPHYTES. 



TABLE C. 



Systematic Table to show the position of the 



HYDKOMEDUSJ3 (CEASPEDOTA) 



(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 cells are always either ectodermal 

 or endodermal. 



Sub-phylum I. CNIDAEIA. 



Ccelenterata with thread-cells. 



CLASS I. HFDROMEDUSJE (CRASPEDOTA). 

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

 without gastral ridges or filaments. 



Order 1. HYDRIDA. 



Solitary polyps without medusoid buds. Both generative 

 products are developed in the ectoderm of the polyp. 



Order 2. HYDROCORALLINJE. 



Colonial Hydromedusae, consisting of a meshwork of ccenosarcal 

 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. TUBULARIJE (GYMNOBLASTEA). 

 Without hydothecae and gonangia. Polyps, \vhen more than 

 one, forming permanent colonies. Generative individuals, 

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



ANTHOMKDUS^B;. The Medusa of this Order. 



Craspedota without otocysts. with ocelli at the base of the 

 tentacles, and with manubrial gonads ; radial canals, usually 

 4, rarely 6 or 8 ; budded from polyps of the Tubulariae. 

 4 Families. 13 Sub-families. 



