106 



THREE CRUISES OF THE " BLAKE. 



while the structure of the ambulacral furrow approaches that 

 of the Comatulae. Hymenodiscus and Brisinga thus form 



Fig. 383. Hymenodiscus Agassizii. 



(Perrier.) 



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

 tional characters. The study of Hymenodiscus, closely allied 



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. 



