POEIPHOEA. 



It With spicala knobbed at one end. 

 H. fucorum. H. seriata. 



incrustans. sanguinea. 



saburrata. macularis. 



segagropila. hystrix. 



With a hard, solid, homogenous texture. 

 H. coalita. H. ficus. 



virgultosa. carnosa. 



hirsuta. , sevosa. 



suberea. maculans. 



mamillaris. 



**** Of doubtful place. 



H. aurea. H. rigida. 



conus. perlevis. 



Ctiona (Grant). Branched or lobed, burrowing 

 into shells, corals or stones, communicating with 

 the exterior by mouths protruding through circular 

 holes in the surface of the foreign body ; interior 

 with anastomosing tubes, and flinty spicula ; sur- 

 face covered with crystalline bodies composed of 

 flint. 



C. celata. C. Alderi. 



gorgonioides. Fig. 5. corallinoides. 



gracilis. \ lobata. 



Howsei. I vastifica. 



Northumbrica. 



Spongia (Linnaeus). Porous, elastic; network 



