14 C03LENTERATA. 



Subgrade A. CCELENTERATA (Diploblastica). 



Metazoans of prevailing radial symmetry, with wide digestive cavity 

 (gastrovascular system). No body-cavity (as blood or lymph-reservoir). 

 Ectoderm and endoderm separated by a supporting lamella (mesoglcea). 

 Asexual reproduction often obtains (gemmation, fission, frequently lead- 

 ing to formation of stocks). The development usually exhibits a meta- 

 morphosis (with planula larva), and often an alternation of generations 

 (sexual and asexual generations alternating). With few exceptions 

 (Spongilla, Hydra, &c.), marine. 



