PLATE XXIII. 



FIG. 



1. MEMBRANIPORA PILOSA, p. 137; normal form. 

 2, 3. , var. a (DENTATA) . 



4. - , var. with three spines. 



5. MlCROPORA CORIACEA, p. 174. 



6. , with avicularia. 



7. , with ooecia. 



* 



8. MlCROPORA COMPLANATA, p. 175. 



9. , more highly magnified, to show the con- 

 striction of the orifice. 



