PLATE 45. 



Geodia acanthylastra Lendenfbld. 

 Figures 1-39. 



1-7. — CKadomes of mesoprotriaenes; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 

 8-15. — Cladomes of anatriaenes; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 

 16. — The cut face of a halved specimen; magnified 3; phot. Zeiss, anastig. 167. 

 17-19. — Groups of spicules from spicule-preparations; magnified 20; phot. Zeiss, planar 20: 



a, large amphioxes; b, plagiotriaenes; c, anatriaenes. 

 20-22. — Dermal amphioxes: 



20-21, magnified 200; phot. Zeiss, apochr. 8, compens. oc. 6; 

 22, magnified 300; phot. Zeiss, apochr, 4, compens. oc. 6. 

 23-25. — Groups of asters from centrifugal spicule-preparations ; magnified 300; phot. Zeiss, apochr. 4, 

 compens. oc. 6: 



a, large acanthtylasters; b, small strongylosphaerasters. 

 26, 27. — Groups of asters from a centrifugal spicule-preparation; magnified 540; u. v. phot. Zeiss, q. 

 monochr. 6, q. oc. 10: 



a, large acanthtylasters; b, small strongylosphaerasters. 



28. — Part of a section through the choanosome; aniline-blue; magnified 200; phot. Zeiss, apochr. 8, 



compens. oc. 6: 



a, young sterraster; b, flagellate chambers. 



29. — View of the sponge; magnified 1.5; phot. Zeiss, anastig. 167. 



30-38. — Plagiotriaenes, dichotriaenes, and cladomes of these spicules; magnified 50; phot. Zeiss, apochr. 

 16, compens. oc. 2: 



30, 35, cladomes of somewhat irregular plagiotriaenes with one lengthened clade; 



31, 32, regular plagiotriaenes; 



33, a plagiotriaene with one bifurcate clade; 



34, cladome of a regular plagiotriaene; 

 36,37, dichotriaenes (possibly foreign); 



38, a plagiotriaene with a shortened, terminally rounded rhabdome. 

 39. — Radial section through the superficial part of the sponge, magnified 100; phot. Zeiss, apochr. 16, 

 compens. oc. 6: 



a, dermal membrane; b, sterraster-armour; e, tufts of dermal rhabds; d, dermal cavities. 



