18 On Two New Genera of Polyzoa. 



EXPLANATION OF PLATE. 



Fig. 1. Diplopora cincia, magnified 50 diameters. 



Fig. la. Side view of two cells. 



Figs. 16 and c. Two views of the same specimen, showing the 

 avicularia, magnified 25 diameters. 



Fig. 2. Densipora corrugata, natural size. 



Fig. 2a. View of surface, showing the opening of the cells, 

 magnified 50 diameters. 



Fig. 26. Section of the same in depression, showing — at a the 

 tubular cells extending the whole thickness, at b the openings of 

 the cells on the sides of a ridge viewed very obliquely, and at c 

 the projecting summit of the ridge, magnified 25 diameters. 



