PLATE 22. 



Geodia mesotriaena var. megana Lendenfeld. 



Figures 1-10. 



1_6._ A series of para tangential sections through a chone and the canals leading to it from the dermal 

 pores (a chonal system) ; magnified 30; phot. Zeiss, planar 20: 



1, first section, the central part in the level of the centre of the concave pore-sieve; 



2, second section, the central part half way down the ectochrotal layer overlying the sterraster- 



armour; 



3, 4. tliird and fourth section, in the distal and proximal part of the sterraster-arraour respectively; 

 .5, fifth section, at the proximal hmit of the sterraster-armour ; 



G, sixth section, through the chone, below the sterraster-armour; 



a, dermal pores (in Fig. 1): b, obUque superficial canals leading from the pores to the chonal 

 canal (Figs. 1, 2); c, chonal canal (Figs. 3-6). 

 7.— Slightly oblique paratangential section, the lower part a, a little higher than the upper part, b, 

 magnified 10; phot. Zeiss, planar .50: 

 c, chones. 

 S.— The central part of the first of the paratangential sections represented in Fig. 1; m.agnified 200; 



phot. Zei.ss, apochr. 8, compens. oc. 6. 

 0.— Part of a radial .section through the choanosome, showing large granular cells; azure; magnified 

 750; phot. Zeiss, horn. unm. apochr. 2, compens. oc. 6: 



a, spindle-shaped granular cells, pointed at both ends; b, a gianular cell, pointetl at only 

 one end. 

 in.— Part of a paratangential section, a transverse section through a chone; magnified 200; phot. 

 Zeiss, apochr. 8, compens. oc. 6: 



a, chonal canal; b, dense mass of small ast«rs; c, circular fibres. 



