36 Invertebrata. 



each appears somewhat umbrella-shaped, and the 

 margin of its disk or swimming bell is adorned with 



FIG. 2t. 



Different stages of Medusoids : A, rooted hydroid colony, natural size ; B, 

 polypite magnified, showing tentacles and swimming bells ; c, D repro- 

 ductive swimming bells, detached and free-swimming. 



little, naked, coloured specks supposed to be eyes, 

 and also with marginal tentacles. A central mouth 

 exists on the under side of the swimming bell, opening 



