PLATE 46. 



Geodia acanthylastra Lendenfeld. 

 Figures 1-21. 



1, 2. — Group of small strongylosphaerasters; magnified 1800, u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10: 



1, focused higher; 2, focused lower. 

 3-7. — Small strongylosphaerasters and groups of such from centrifugal spicule-preparations; magnified 



1800; u. V. phot. Zeiss, q. monochr. 1.7, q. oc. 10. 

 8, 9. — Sterrasters; magnified 300; phot. Zeiss, apochr. 4, compens. oc. 6. 

 10, 11. — Large oxysphaerasters ; magnified 1800; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10: 



10, focused lower; 11, focused higher. 

 12, 13. — Large oxysphaeraster; magnified 1800; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10: 



12, focused lower; 13, focused higher. 

 14-16. — The umbilicus of a sterraster and the adjacent parts of its surface; magnified 1800; u. v. phot. 

 Zeiss, q. monochr. 1.7, q. oc. 10: 



14, focused high; 15, focused intermediate; 16, focused low. 

 17-19. — The umbilicus of a sterraster and the adjacent parts of its surface; magnified 1800; u. v. phot. 

 Zeiss, q. monochr. 1.7, q. oc. 10: 



17, focused high; 18, focused intermediate; 19, focused low. 



20. — Radial section through the superficial part of the sponge; magnified 30; phot. Zeiss, planar 20: 



a, protruding minute dermal rhabds; b, dermal membrane; c, sterraster-armour; d, pro- 

 truding mesoproclades; e, choanosome. 



21. — A pore-sieve; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 



