CHARACTERISTIC DEEP-SEA TYPES. 



CRINOIDS. 



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. — Myzostonia filicaiida. 

 (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 filicaiida, the host of Autedon Ilar/enii, 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 

 the cyst formed by 31. cystico- 



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

 nalis, they resemble plant galls. 



Fig. 421. Fig. 421 a. 



Myzostoma eysticolum. ^. (Von Graff.) 



Parasite of Actinometra meridionalis. 



