mmmmmmmmmmm 



1 B ^ ■ 



M^V 



■man 



Mmm 







. 



• 



:; 



Plate 23. 





Micropliotographs of thick unstained preparations showing skeletal arrangement. 



Ficr 



1. Tylodesma vestibularis. 



a 



2. 



u 



a 



Section vertical to surface of -sponge, which is repre- 

 sented by right margin of figure. Hexactinellid 

 skeleton appearing in deeper part of section ; x 25. 



Dermal membrane covering in a large vestibular cavity. 

 Upper right margin represents edge of osculum ; 

 x 15. 



Dermal membrane covering in, and adjoining, a medium- 

 sized vestibular cavity ; x 15. 



4. Iophon indentatus. Section vertical to surface, which is represented by right 



margin of figure. Section includes large part of the 

 Gorgonia axis (to the left) ; x 25. 



3. 





*, 



i 









:; 



b I 



« 



:: 





i; 





■ 



