106 THREE CRUISES OF THE “BLAKE.” 
while the structure of the ambulaeral furrow approaches that 
of the Comatule. Hymenodiscus and Brisinga thus form 
Fig. 383. — Hymenodiscus Agassizi. 1:5. (Perrier.) 
among starfishes a very peculiar family, marked by most excep- 
tional characters. The study of Hymenodiscus, closely allied 
Fig. 385. Magnified spine. 
Hymenodiscus Agassizi. (Perrier, ) 
to the northern Brisinga, has had an important bearing on the 
morphology of the starfish skeleton. 
