134 



THE INVERTEBRATA 



colony is continuous and common to all its members. Ciliary 

 currents distribute the food obtained by some individuals to those 

 parts of the colony where feeding is not taking place. As in all 



Fig. 112. Part of a branch of Obelia sp. To the left a portion is shown in 

 section. After Parker and Haswell. ect. ectoderm; end. endoderm; mth. 

 mouth; coe. coelenteron; esc. coenosarc; psc. perisarc; hth. hydrotheca; 

 his. blastostyle; med. medusa-bud; ^Z^. gonotheca. 



Calyptoblastea the coenosarc is completely invested by the cuticular 

 secretion, the perisarc, composed of chitin and produced to form cups 

 round the hydranths {hydrothecae) and the blastostyles (gonothecae). 



