Plate XVI. 



Staurocalyptii-s plcorlioplddcs. 1j. P. 222. 



Fi"-. J. S. C. M. No. 226. A part of the wall cut off and the ga^tral 



surface exposed. Nat. size. 

 Fif, 2. Another entire specimen. S. C. M. No. 415. Nat. size. 

 Figs. 3-.5. Derinalia. .300 x. 



Fif. 6. Gastral diactin of a moderately large size. 300 X . 

 Fig. 7. Normally developed oxyhexaster. 300 x . 

 Fjo-, 8. Malformed oxyhexaster, observed but once. 300 x . 

 Fig. Î), 10. Discoctasters of the larger size. 300 x . 

 Fi«»'. 11. Part of a very small discoctaster. 300 x. 

 Fiy;. 12. Microdiscohexaster. 300 x . 

 Fig. 13. Part of the paratangential ray of a prostal pentactin, to show 



the roughness of surface caused Ijy minute and pointed microtu- 



l)ercles. 300 x . 

 Fig. 14. Spicules in and un a conuhis of the sponge-surface. Two i)rostal, 



paratropal oxypentactins and a part of a prostal oxydiactin. 



About 30 X. 

 Fig. 1.5. Surface view of the ectosome, with dermalia which are mostly 



diactins. 60 X . 

 Fi<''. 16. Surface view of the eudosome, with diactinic gastralia. 60 X . 



