PLATE 20. 



Geodia amphistrongyla Lendenfeld. 

 Figures 1-41. 



1-3. — Choanosomal amphistrong-yles ; magnified 30 ; phot. Zeiss, planar 20. 



4. — Cladome of a mesanatriaene with oblique epirhabd; magnified 200; phot. Zeiss, apochr. 8, com- 

 pens. oc. 6. 



5; 6. — Cladomes of anatriaenes; magnified 200; phot. Zeiss, apochr. 8, compens. oc. 6: 



5, with smaller clade-rhabdome angle; 



6, with larger clade-rhabdome angle. 



7, 8. — Cladomes of mesoproclades, magnified 200; phot. Zeiss, apochr. 8, compens. oc. 6: 



7, of a mesopromonaene; 



8, of a mesoprotriaene. 



9. — Part of radial section through the distal portion of the choanosome, showing a cluster of young 



sterrasters in. situ; magnified 200; phot. Zeiss, apochr. 8, compens. oc. 6. 



10. — Cladome of an anatriaene; magnified 300; phot. Zeiss, hom. imm. apochr. 2. 



11. — Cladome of an anatriaene; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 



12. — Large choanosomal oxyaster; magnified 450; u. v. phot. Zeiss, q. monochr. 6, q. oc. 10. 



13. 14. — Parts (rays) of large choanosomal oxyasters; magnified 750; phot. Zeiss, hom. imm. apochr. 



2, compens. oc. 6. 



15, 16. — Parts (rays) of large choanosomal oxyasters; magnified 1800; u. v. phot. Zeiss, q. monochr. 

 1.7, q. oc. 10. 



17. — One end of a cylindrical amphi.strongyle with thickenings; magnified 200; phot. Zeiss, apochr. 

 8, compens. oc. 6. 



18-21. — Large choanosomal rhabds and parts of such; magnified 100; phot. Zeiss, apochr. 100, com- 

 pens. oc. 6.: 



18, a short anisoactine, somewhat style-like amphistrongyla; 



19, a larger, nearly isoactine, cylindrical amphistrongyle; 



20, the rounded end of a large style (the pointed end of this spicule is represented in Fig. 21); 



21, the pointed end of a large style (the rounded end of this spicule is represented in Fig. 20). 

 22-25. — Cladomes of plagiotriaenes and derivates of such: magnified 100; phot. Zeiss, apochr. 16, 



compens. oc. 6: 



22, cladome of a regular plagiotriaene with short clades; 



23, cladome of a plagiomonaene with normal rhabdome and simple clade; 



24, an orthodichomonaene with shortened rhabdome ; 



25, cladome of a regular plagiotriaene with long clades. 



26-30. — Groups of microscleres from a centrifugal spicule-preparation ; magnified 300: 

 26-28, 30, phot. Zeiss, apochr. 4, compens. oc. 6; 

 29, phot. Zeiss, hom. imm. apochr. 2; 



a, large choanosomal oxyasters; b, large oxysphaerasters ; c, small strongylosphaerasters; d, 

 young sterrasters. 



31. — View of the sponge; magnified 1.1 ; phot. Zeiss, anastig. 480 / 412. 



32. — Group of sterrasters from a spicule-preparation; magnified 200; phot. Zeiss, apochr. 8, compens. 



oc. 6. 



33. — Radial section through the superficial part of the sponge; magnified 20; phot. Zeiss, planar 



20: 



a, cortex; b, a chone; c, subcortical cavities; d, choanosome. 

 34-36. — Small strongylosphaerasters, two single ones and a group, from a centrifugal spicule-prepa- 

 ration; magnified 1800; u. v. phot. Zeiss, monochr. 1.7, q. oc. 10. 

 37, 38. — The umbilicus of a sterraster and the adjacent parts; magnified 1800; u. v phot. Zeiss, q. 

 monochr. 1.7, q. oc. 10: 

 37, focused lower; 38, focused higher. 



39. — Radial .section through the superficial part of the sponge; magnified 10; phot. Zeiss, planar 50: 



a, cortex; c, subcortical cavities; d, choanosome. 



40, 41. Part of the surface of the side of a sterraster; magnified 1800; u. v. phot. Zeiss, q. monochr. 



1.7, q. oc. 10: 

 40, focused lower; 41, focased higher. 



