PLATE 15. 



Sidonops angulata Lendenfeld. 



Figs. 1, 2, 4, 9. — var. megana Lendenfeld (massive form). 

 Figs. 3, 7, 8, 11.— var. megana Lendenfeld (lobose form). 

 Figs. 5, 6, 12. — var. orthotriaena Lendenfeld. 

 Fig. 10. — var. microana Lendenfeld. 



1, 2. — Two views of the umbilicus and the adjacent parts of the surface of a sterraster of the massive 

 specimen of var. megana; magnified 1800; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10: 



I, focused higher: 2, focused lower. 



3. — The umbilicus and the adjacent parts of the surface of a sterraster of the lobose specimen of var. 



megana ; magnified 1800; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10. 



4. — Part of a section through the choanosome of the massive specimen of var. megana; haematoxylin; 



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

 a, masses of small cells; b, lumen of a canal. 



5. 6. — Part of the surface opposite to the umbilicus of a sterraster of var. orthotriaena; magnified 1800; 



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

 5, focused higher; 6, focused lower. 



7. — Part of a para tangential section of the cortex of the lobose specimen of var. megana; magnified 200; 



phot. Zeiss, apochr. 8, compens. oc. 6: 



a, blunt cones protruding into a radial cortical canal; b, lumen of the radial cortical canal; 

 c, sterrasters. 



8. — Part of a paratangential section of the lobose specimen of var. megana, transverse through a chone; 



magnified 200; phot. Zeiss, apochr. 8, compens. oc. 6: 

 a, po.sition of the (closed) chonal canal. 

 9-12. — Groups of sterrasters from spicule-preparations: magnified 200; phot. Zeiss, apochr. 8, compens. 

 oc. 6: 



9, of the massive specimen of var. megana ; 



10, of var. microana; 



II, of the lobose specimen of var. megana; 

 12, of var. orthotriaena. 



