Geodia agassizii Lendenfeld (young) from Station 4425. 



Figures 1-46. 



1. — Part of a radial section through the choanosome; haematoxylin; magnified 200; phot. Zeiss, 

 apochr. S, compens. oc. 6: 

 a, flagellate chambers. 

 2. 3. — Small sphaerasters; magnified 1800; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10: 

 2, with conical, pointed rays; 

 'i, with cylindrical, truncate rays- 

 4.- — Group of cuasters from a centrifugal .spicuk-preparalion; magnified 300; u. v. phot. Zeis.s, q. mon- 

 ochr. 1.7. 

 5. — Part of a radial section through the choano-some; haematoxylin; magnified 10; phot. Zeiss, planar 

 50: 



a, an efferent canal with constrictions. 

 6, 7. — Large oxy.sphaerastcrs; magnifieil ISOO; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10. 

 8. — Part of a radial section; magnified 10; phot. Zeiss, planar 50: 



a, sterrastcr-armour. 

 9, 10. — Large choanosomal amphioxes; magnified 30; phot. Zeiss, planar 20. 

 11. — Part of a radial section; magnified 10; phot. Zeiss, planar 50: 



a, sterraster-armour; b, protruding parts of spicules forming the spicule-fur. 

 12. — Part of a radial section; magnified 10; phot. Zei.ss, planar 50: 



a, sterraster-armour; b, rhabdome of an orthotriaene with rounded and thickened acladomal 

 end. 

 13-39. — Sterroids and sterrasters; magnified 300; phot. Zeiss, apochr. 4, compens. oc. 6: 



13, 15, 17, 19, 21, 23. 25, 27, and 29-39, the highest part of the upper surface in focus; 



14, 16, 18, 20, 22, 24, 26, 28, the spicules represented above them in Figs. 13, 15, 17, 19, 21, 23, 25, 

 27, focused lower. 



40-42. — Cladonies of mesoproclades ; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6: 

 40, 41, of regular slender ones; 



42, of a stout one with one rudimentary clade. (This spicule may be foreign). 

 43-46. — Cladonies of anaclades; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6: 



43, 46, of regular anatriaenes with well-developed, pointed clades; 



44, of an anadiaene with well-developed pointed clades; 



45, of an irregular anatriaene with small clades, one of which is shortened and rounded at the end. 



