PLATE 37. 



Geodia micropora Lendenfeld. 

 Figures 1-14. 



1. — Portion of a radial section through the superficial part of the sponge: magnified 20; phot. Zeiss, 



planar 20: 

 a, cortex. 



2. — Portion of a radial section through the superficial part of the sponge; magnified 7.5; phot. Zeiss, 



planar .50: 



a, cortex; b, large efferent canal-stem. 



3. — Portion of a radial section through the superficial part of the sponge; magnified 100; phot. Zeiss, 



apochr. 16, compens. oc. 6: 



a, dermal membrane; b, tufts of small dermal rhabds in position in the dermal layer; c, 

 sterraster-armour; tl, subcortical cavity; e, small dermal rhabds still situated subcorti- 

 cally; f, large subcortical triaenes. 

 4-7. — Orthoplagiotriaenes; magnified 50; phot. Zeiss, apochr. 16, compens. oc. 4. 



8, 9. — Surface views of thin superficial, paratangential sections in transmitted light; magnified 10; 

 phot. Zeiss, planar 50: 



8, part of an afferent area ; 



9, part of an efferent area. 



10, 11. — Chelotrops; magnified 50; phot. Zeiss, apochr. 16, compens. oc. 4. 



12. — A pore-sieve from an afferent area; magnified 50; phot. Zeiss, apochr. 16, compens. oc. 4. 



13. — A group of pore-sieves from an efferent area; magnified 50; phot. Zeiss, apochr. 16, compens. oc. 4. 



14. — Part of a radial section through the choanosome; congo-red; magnified 100; phot. Zeiss, apochr. 



16, compens. oc. 6. 



Geodia japonica (Sollas). 

 Figures 15-30. 



15-17. — Cladomes of orthotriaenes; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6: 



15, .side- view of an orthotriaene-cladome with terminally irregular clades; 



16, side-view of an orthotriaene with regular clades; 



17, an orthotriaene-cladome (with the rhabdome broken off) seen from below. 

 18-21. — Large choanosomal amphioxes; magnified 20; phot. Zeiss, planar 20. 



22. — Group of megascleres from a spicule-preparation; magnified 20; phot. Zeiss, planar 20. 



a, ordinary, large choano.somal amphioxes; b, orthotriaene with regular clades; c, ortho- 

 triaene with an irregular clade; d, smaller, slender curved amphiox; e, large anatriaene. 

 23-28. — Orthotriaenes; magnified 20; phot. Zeiss, planar 20: 

 23-27, with fairly straight rhabdome; 

 28, with curved rhabdome. 

 29, 30. — Large anatriaenes; magnified 20; phot. Zeiss, planar 20. 



