106 



THREE CRUISES OF THE " BLAKE 



while the structure of the ambulacral furrow approaches that 

 of the Comatulse. Hymenodiscus and Brisinga thus form 



Fig. 383. — Hymenodiscus Agassizii. i^ 5 -. (Perrier.) 



among starfishes a very peculiar family, marked by most excep- 

 tional characters. The study of Hymenodiscus, closely allied 



r; 



fr A 



Fig- 384. \- Fig. 385. Magnified spine. 



Hymenodiscus Agassizii. (Perrier. ) 



to the northern Brisinga, has had an important bearing on the 

 morphology of the starfish skeleton. 



