PLATE XXI. 



Fig. io. The adult stage of Membranipora sandalia, in which the surface is 

 covered with a fine calcareous layer, obscuring the network previously 

 formed. A large sessile avicularium {av.) is found upon the area be- 

 low the aperture. 



11. Entalophora capitata sp. nov. Natural size of the purple variety with 

 elliptical base. Orifices of the upright zoecia (or.). 



12. The white variety of the same, natural size. 



13. The smaller of the two columns represented by fig. 11. Only part 

 of the base {bas) shown in the drawing. 



14. Alcyonidiufti cervicornis sp. nov. A colony, natural size. 



15. Part of the siu-face of the same, showing spines, and orifices of the 

 zoecia (or.). 



Figs. 16 and 17. Two of the spines of the same, showing two modes of branch- 

 ing. The drawing is intended to show the branching top of the spine 

 as it appears when viewed directly from above. 



(340) 



