PLATE 7. 



Sidonops oxyastra Lendenfeld. 

 Figures 1-20. 



I, 2. — Two radial sections through a lobe of the sponge; magnified 10; phot. Zeiss, planar 50: 



1, a thin section stained with haematoxylin and aniline-blue; 



2, a thick unstained section ; 



a, sterraster-armour ; b, monaxonid sponge attached to the Sidonops; c, afferent cortical 

 canals; d, wide efferent canals; e, efferent pores. 

 3-5. — Groups of asters from a centrifugal spicule-preparation ; magnified 300; phot. Zeiss, apochr. 4, 

 compens. oc. 6: 



a, large oxyasters; b, small oxysphaerasters and oxyasters; c, large oxysphaeraster. 



6. — Part of a radial section through a region of the cortex bearing afferent pores ; magnified 20 ; phot. 



Zeiss, planar 20: 



a, sterraster-armour; b, monaxonid sponge attached to the Sidonops. 



7, 8. — Large oxyasters from centrifugal spicule-preparations; magnified 900; u. v. phot. Zeiss, q. mon- 



ochr. 1.7, q. oc. 5. 



9, 10. — Group of small oxysphaerasters (oxyasters) from a centrifugal spicule-preparation; magnified 

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

 9, focused higher; 10, focused lower. 



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



11, focused higher; 12, focused lower. 

 13-15. — Large oxyasters; magnified 1800; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10. 

 16-18. — Small oxysphaerasters (oxyasters); magnified 1800; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 

 10. 



19, 20. — Large oxysphaeraster; magnified ISOO; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10: 

 19, focused higher; 20, focused lower. 



