24 



(iUIUE TO THE CORAL GALLERY. 



High Cases Class II. SILICEA {sihx, flint). Skeleton siliceous, horny, or 



l.-vi. and absent. 



Table Cases yW 4 



1 and 2 A, B, "' ' „ 



a 



A. Clathrina hlanca X 20. b. The same x 80 (partly diagiamraatie). a,oscule; 

 b, pores ; c, spicules ; d, portion of wall turned back. c. Transverse section 

 of sponge (diagrammatic). D. A tliree-rayed spicule x 300 diameters. 

 E. Collar cells x 1,200 diameters. (After E. A. Minchin.) 



Sub-Class I. Hexactinellida {hex, six ; aMis, ray). Six- Ray or 

 Glass Sponges. Siliceous spicules typically with three axes and six rays. 



