PLATE 23. 



Geodia mesotriaena Lendenfeld. 



Figs. 1, 2. — var. microana Lendenfeld. 



Figs. 3, 5, 6, 8, 9. — var. pachana Lendenfeld. 

 Figs. 4, 7, 10-25. — var. megana Lendenfeld. 



1-12. — C!ladomes of anatriaenes; magnified 100; phot. Zeiss, apochr. 18, compens. oc. 6: 

 1, 2, of fully developed anatriaenes of var. microana; 



3, 5, 6, 8, 9, of fully developed anatriaenes of var. pachana; 



4, 7, of a young anatriaene of var. megana; 



10-12, of fully developed anatriaenes of var. megana. 

 13-19. — Cladomes of teloclades and mesoclades of var. megana; magnified 100; phot. Zeiss, apochr. 

 16, compens. oc. 6: 



13, of an irregular mesoprotriaeiie with branches forming a second verticil of clades on the 

 epirhabd ; 



14, of a mesoprotriaene with one clade abruptly bent, and one strongyle; 



15, of an irregular protriaene with one clade nearly vertical; 



16, of a regular orthotriaene ; , 



17, of an irregular mesanatriaene with strongly deflected epirhabd; 



18, of a young regular mesoprotriaene ; . 



19, of a regular me.soprotriaene fully developed. 



20-23. — Cladomes of orthotriaenes of var. megana; magnified 50; phot. Zeiss, apochr. 16, compens. 

 oc. 4: 



20, of an orthotriaene fully developed with clades not very different in size; 



21, of a young quite regular orthotriaene; 



22, of an orthotriaene fully developed with one clade much shorter than the others; 



23, of an orthotriaene fully developed with one clade abruptly bent and shorter than the others. 

 24, 25. — Radial section through a part of the cortex and the adjacent choanosome of var. megana: 



24, magnified 10; phot. Zeiss, planar 50; 



25, (a part of 24) magnified 30; phot., Zeiss, planar 20; 



a, outer surface: b, sterraster-armour ; c, superficial canals; d, chone; e, radial main choano- 

 somal canal; f, tissue free from flagellate chambers surrounding the radial main choano- 

 somal canal; g, tissue containing flagellate chambers; h, radial spicule bundles; i, small, 

 more or less radial, dermal rhabds protruding beyond the surface; k, chonal canal. 



