PLATE IV. 



page. 

 figs, i 9 Lyidium Zitteli n. sp. Detached spicules of various forms ; 



in Figs. 1 , 3 , spicules are shown naturally attached together 5 1 



Figs. 10 /<? Lyidium cretacea n. sp. Detached spicules 54 



Fig. 13 The same. Fragment of the skeleton showing four spicules 



naturally attached together 54 



Figs. 14 23 Detached spicules of Carterella, sp 54 



Figs. 24 jo Ragadinia annulata, n. sp. Various forms of the surface 



spicules 58 



Figs. 3 1 34 Racodiscula and allied Genera. Surface spicules 60 



Figs- 35 4 2 Plinthosella squamosa, Zittel. Detached and combined spicules 



of the skeleton. Figs. 36, 40, 42 show fragments in which 



the spicules are combined together 56 



Figs. 43 46 The same. Differently shaped spicules of the surface layer 



of this sponge 56 



All the figures on this Plate are drawn to the same scale cf 20 diameters by 

 means of the Camera lucida. 



