PLATE 36. 



Hyalonema (Hyalonema) obtusum gracilis Lendenfeld. 

 Figures 1-45. 



1-25. — Tetractine acanthophores of the sheaths enclosmg the large stalk-spicules in the basal part of 

 the sponge-body; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6: 

 1-13, forms with rays not vei-y different in size; 

 14-25, forms in which one or two of the rays are markedly reduced. 



26. — Part of an axial section thi-ough the basal part of the sponge-body; magnified 30; phot. Zeiss, 



planar 20 mm.: 



a, space previously occupied by a large stalk-spicule. 



27, 28. — Ray-ends of the tetractine acanthophore of the sheaths enclosing the large stalk-spicules in 



the basal part of the sponge-body; magnified 300; phot. Zeiss, apochr. 4, compens. oc. 6. 

 29-36. — Rhabd-aeanthophores of the sheaths enclosing the large stalk-spicules in the basal part of the 

 sponge-body; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6: 



29, 32-36, tyiostyles; 



30, amphistrongyle ; 



31, centrotyle style. 



37, 38. — The two ends of the amphistrongyle acanthophore represented in fig. 30; magnified 300; phot. 



Zeiss, apochr. 4, compens. oc. 6. 

 39-44. — Diactme acanthophores of the sheaths enclosing the large stalk-spicules in the basal part of the 

 sponge-body; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6: 

 39, an angularly bent, slender, centrotyle diactine; 

 40-44, slightly curved, stout, centrotyle diactines. 

 45. — Strongly curved style acanthophore of the sheaths enclosing the large stalk-spicules in the basal 

 part of the sponge-body; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 



