CHARACTERISTIC DEEP-SEA TYPES. CR1NOIDS. 



127 



of two characteristic species of these worms, strangely modified 

 to adapt themselves to the peculiar conditions of their habitat. 



The organs of the body are arranged radially, and the mus- 

 cular system so admirably adapted for attachment is wanting in 



Fig. 419. Myzostoma filicauda. 

 - (Von Graff.) 



Fig. 420. Myzostoma Agassizii. 

 \-. (Von Graff.) 



the type which moves about freely on its host. In another 

 group, a male and female inhabit a common cyst, caused by the 

 presence of the parasite on the arm-joint or pinnule. Myzos- 

 toma filicauda, the host of Antedon Hayenii, is one of the 

 species with caudal append- 

 ages (Fig. 419), while Myzos- 

 toma Agassizii represents a 

 type with long filiform cirri. 

 (Fig. 420.) Another group 

 forming no cyst has only short 

 cirri. The cysts are sometimes 

 sausage-shaped and situated on 

 the disk of the host, or, like 



Fig. 421. Fig. 421 a. 



Myzostoma cysticolum. ^. (Von Graff.) 



Parasite of Actinometra meridionalis. 



the cyst formed by M. cystico- 

 lum (Figs. 421, 421 a) on the arms of Actinometra meridio- 

 nalis, they resemble plant galls. 



