PLATE 107. 



Hyalonema (Prionema) crassum Lendenfeld. 

 Figures 1-20. 



1, 2. — A large serrated raacramphidisc; magnified 500; phot. Zeiss, apochr. 8, compens. oc. 12: 



1, focussed high, on the uppermost teeth; 2, focussed lower, on the centre of the shaft. 

 '■i. 4. — A terminal anchor of a large serrated macramphidisc; magnified 500, phot. Zeiss, H. I. apochr. 2 

 compens. oe. 4: 



3, focussed high; 4, focussed a little lower. 

 5. — A medium-sized serrated macramphidisc; magnified 500;*phot. Zeiss, apochr. 8, compens. oc. 12 

 6-15. — Paratangential superficial amphioxcs; magnified 50; phot. Zeiss, apochr. 16, compens. oc. 2: 



6-10, slender ones from the dermal membrane; 



11-15, stouter ones from the gastral membrane. 

 16. — View of the largest specimen; natural size; phot. Zeiss, anastig. 480/412 mm. 

 17-20. — Parts of an anchor-tooth of a large serrated macramphidisc; magnified 2000; u. v. phot 

 Zeiss, q. monochr. 1.7, q. oc. 10: 



17, the tip of the tooth, focussed high; 



18, the distal part of the same tooth, focussed lower; 19, focussed still lower; 

 20, the middle-part of the same tooth, focussed lowest. 



