PLATE 12. 



Sidonops an^ata Lendenfeld. 



Figs. 1-4, 16, 19. — var. magana Lendenfeld (lobose form). 



Figs. 5-8, 17, 20. — var. megana Lendenfeld (massive form). 



Figs. 9, 10. — var. orthotriaena Lendenfeld. 



Figs. 11-1.5, 18, 21, 22. — var. microana Lendenfeld. 



1-14. — Cladomes of anaclades; magnified 200; phot. Zeiss, apochr. 8, compens. oc. 6: 

 1-4, of tlie lobose specimen of var. megana; 

 5-8, of the ma.ssive specimen of var. megaiia; 

 9, 10, of var. orthotriaena; 

 11-14, of var. microana; 



1, 5, of anatriaenes with long equal clades; 



2, 4, 12-14, of anatriaenes with short equal clades; 



3, 6, 8, 9, of anatriaenes with medium-sized equal clades; 

 7, of an anatriaene with medium-sized unequal clades; 

 10, 11, of anadiaenes w^ith short clades. 



15. — The acladoraal end of the anatriaene of var. microana, the cladome of which is represented in Fig. 



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

 16, 17. — Groups of spicules from spicule-preparations ; magnified 10; phot. Zeiss, planar 50: 



16, of the lobo,se specimen of var. megana; 



17, of the massive specimen of var. megana; 



a, slender, dermal, simply curved amphioxes; b, slender, denual, angularly bent amphiox; 

 c, stout, choanosomal amphioxes ; d, plagiotriaenes. 

 18-20.— Views of three of the specimens; phot. Zeiss, anastig. 480 / 412: 



18, var. microana; magnified 1.1; 



19, the lobose specimen of var. megana; reduced 1 : 0.86; 



20, the mas-sive specimen of var. megana; reduced 1 : 0.9. 



21,22. — Groups of plagiotriaenes from a spicule-preparation of var. microana; magnified 10; phot. 

 Zeiss, planar, 50. 



