EXPLANATION OF PLATE VIII. 



Fig. I. — Mass formed of shells of Siliquaria muricata (Born.) and 

 the sponge Spongosorites iopsenti, Dendy, viewed from 

 above. (Scale about f.) 



,, 2. — Mass formed of shells of Spiroglyphus cummingi, Morch, 

 and the sponge Racodiscula sceptrellifera var. spirogly- 

 phi nov.^ viewed from below. (vScale about f.) 



In both figures the lower end of the mass is obscured to a 

 slight extent. 



