THE HYDRA AND ITS ALLIES 



213 



beautiful inhabitants of the sea. Those who have crossed 

 the Atlantic are acquainted with the " Portuguese man-of- 



fon. 



FIG. 200. Physalia arethusa. 

 Nat. size. After Agassiz. 



net 



nlc 



FIG. 201. Halistemma terge- 

 stinum. The entire colony. 

 cw, coenosarc; dz, dactylo- 

 zooid ; hph, hydrophyllium or 



bract; net, nectocalyx or swimming-bell; ntc, battery of nematocysts; 

 p, polyp; pn, pneumatophore or float; t, tentacle. After Glaus. 



