PLATE 33. 



Hyalonema (Hyalonema) obtusum gracilis Lendenfeld. 

 ^ Figures 1-24. 



1, 2. — Centrotyle amphioxes; magnified 100; phot. Zeiss, apoclir. 16, compens. oc. 6. 



3. — Group of small hypodermal amphioxes; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 



4. — Small hypodermal amphiox; magnified 300; phot. Zeiss, apochr. 4, compens. oc. 6. 



5-14.^ — Side-views of hypodermal pentactincs; magnified 50; phot. Zei-ss, achr. aa, compens. oc. 2. 



15. — View of the sponge; magnified 1.1; phot. Zeiss, anastig. 480/412 mm. 



16. — View of the sectioned face of the sponge cut in half longitudinally and axially; magnified 2; phot. 



Zeiss, anastig. 167 mm.: 



a, oral cone; b, lower end (place where the stalk is broken off). 



17. — The tip of a lateral ray of a hypodermal pentactine; magnified 300; phot. Zeiss, apochr. 4, compens. 



oc. 6. 



18-23. — Rhabds of the supporting skeleton; magnified 50; phot. Zeiss, achr. aa, compens. oc. 2: 

 18, 19, small, shghtly centrotyle amphioxes; 



20, tylostyle; 



21, medium centrotyle amphiox; 



22, medium amphiox; 



23, large amphiox. 



24. — Oblique apical view of a hypodermal pentactine; magnified 50; phot. Zeiss, achr. aa, compens. 

 oc. 2. 



