24 
GUIDE TO THE CORAL GALLERY. 
High Cases 
I.-VI. and 
Table Cases 
1 and 2 a, b, 
Class TI. SILICEA ( silex , flint). Skeleton siliceous, horny, or 
absent. 
a. Clathrina blcinca x 20. b. The same x 80 (partly diagrammatic), a, oscule ; 
b, pores ; c, spicules ; d , portion of wall turned back. c. Transverse section 
of sponge (diagrammatic), d. A three-rayed spicule X 300 diameters. 
e. Collar cells x 1,200 diameters. (After E. A. Minchin.) 
Note. — In Fig. B, the spicules ought not to have been drawn close up to the 
margin of the oscule ; also the figure is too broad and the pores far too large. 
Sub-Class I. Hexactinellida (hex, six ; aktis, ray). Six-Ray or 
Glass Sponges. Siliceous spicules typically with three axes and six rays. 
