PLATE XXI. 



FIG. 



1. MEMBRANIPORA FLEMINGII, p. 1G2; from a fully 



developed specimen. 



a,l b. , young zooecia with the full com- 

 plement of spines ; avicularia partially developed. 



2 } 3. , var., showing the produced portions 



of the cell below. 



4. MEMBRANIPORA CORNIGERA, p. 164. See Plate 

 XXII. fig. 4. 



5, 6. MEMBRANIPORA AURITA, p. 159. 

 7. SETOSELLA VULNERATA, p. 181. 



