HYLUM CCELENTERATA 



FIG. 50. Halistemma tergestinum. A, the entire colony; B, a single group of 

 zooids; cos, coenosarc; dz, dactylozooid ; hph, hydrophy Ilium or bract: net, 

 nectocalyx or swimming-bell; ntc. battery of nematocysts; p. polype; />, 

 pneumatophore or float; J, *', sporocysts; ^tentacle. (After Claus.) 



