PLATE XXI. 



Brissopsis lyrifera, / 1, 2- 



1. Seen from actinal side, nat. size (from Norway). 



2. Seen from above, nat. size. 



Schizaster fragilis, / 5. 



3. Seen from above, nat. size (from Norway). 



Metalia pectoralis, f. 4, 5. 



4. Seen from actinal side, f nat. size. 



6. Seen from abactinal pole, f nat. size. 



