PLATE 40. 



Hyalonema (Hyalonema) obtusum robusta Lendenfeld. 

 Figures 1-22. 



1, 2. — Large macramphidiscs; magnified 500; phot. Zeiss, apochr. 4, compens. oc. 12. 

 3-5. — Pillules; magnified 300; phot. Zeiss, apochr. 4, compens. oc. 6: 



3, a gastral hexactine pinule; 



4, a dermal pentactine pinule with reducetl lateral rays; 



5, a dermal pentactine pinule. 



6-^15. — Microhexactines and microhexactine-derivates; magnified 500; phot. Zeiss, H. I. apochr. 2, 

 compens. oc. 4: 



6, 7, regular microhexactines; 



8, a pentactine microhexactine-derivate; 



9, a microhexactine with two opposite rays much longer than the others; 



10, a diactine microhexactine-derivate, the fully developed rays of which are not opposite; 



11, a triactine microhexactine-derivate; 



12, 13, diactine (centrotyle), microhexactine-derivates, the fully developed rays of which arc 

 opposite; 



14, 15, monactine (tylostyle or tyle) microhexactine-derivates. 

 16, 17. — Small micramphidiscs; magnified 500; phot. Zeiss, H. I. apochr. 2, compens. oc. 4. 



18. — A young micramphidisc; magnified 500; phot. Zeiss, H. I. apochr. 2, compens. oc. 4. 



19. — Part of an u-regular macramphidisc; magnified 500; phot. Zeiss, apochr. 4, compens. oc. 12. 



20. — Group of microscleres from a centrifuge spicule-preparation; magnified 500; phot. Zeiss, H. I. 



apochr. 2, compens. oc. 4: 



a, small micramphidiscs; b, microhexactine; c, microhexactine-derivate with only two 

 opposite, fully developed rays. 



21. 22. — Parts of the upper end of a large stalk-spicule; magnified 300; phot. Zeiss, apochr. 4, compens. 



oc. 6, 



