PLATE 8. 



Sidonops oxyastra Lendenfeld. 

 Figures 1-15. 



1-3. — Stcrrasters; magnified 300: 



1, phot. Zeiss, apochr. 4, compens. oc. 6; 



2, 3 phot. Zeiss, hom. imm. apochr. 2. 



4. — Group of spicules from a spicule-preparation ; magnified 30; phot. Zeiss, planar 20: 



a, large amphioxes; b, lateral views of plagiotriacnes; c, apical view of a plagiotriaene-cladome. 



5. — Group of large amphioxes from a spicule-preparation; magnified 30; phot. Zeiss, planar 20. 



6-8. — Part of the lateral surface of a thick-rayed sterraster; magnified 1800; u. v. phot. Zeiss, q. 

 monochr. 1.7, q. oc. 10: 

 6, focused high ; 7, focused lower; 8, focused still lower. 



9. — Part of the lateral surface of a sterraster not quite fully developed; magnified 1800; u. v. phot. 



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



10, 11. — Part of the lateral surface of a thin-rayed sterraster; magnified 1800; u. v. phot. Zeiss, q. 



monochr. 1.7, q. oc. 10: 

 10, focused higher; 11, focused lower. 



12. — Sterraster; magnified 1000; phot. Zeiss, hom. imm. apochr. 2, compens. oc. 6; the centrum of the 



spicule in focus: 



a, rosette of central granules; b, umbiUcus. 



13, 14. — Views of parts of the surface (superficial paratangential sections) with transmitted light; 



magnified 20; phot. Zeiss, planar 20: 



13, of a region bearing afferent pores; 



14, of a region bearing efferent pores. 



15. — Part of a region of the surface with afferent pores; magnified 100; phot. Zeiss, apochr. 16, compens. 

 oc. 6. 



