108 



INYEin'EBltATE AXIMALS. 



When yoinig, the ComatiiJa is so different in apjjearance from the 

 adult, that it was originally descrilied as a distinct animal. It con- 

 sists now uf a little cup-sliajied difc with ten radiating ai-ms above, 



jirodnced by the splitting into 

 two of five primary rays, and 

 furnished inferiorly with a 

 little flexible column or stalk 

 composed of a number of cal- 

 careoiis joints. B}' this jointed 

 stem the body is at this period 

 of life fixed to sea -weeds 

 or otlier submarine objects. 

 When sutticieiitly mature, 

 however, the body drops ott' 

 its stalk, and tlien only re- 

 quires to grow in size to 

 become a fully developed 

 Comatula. 



The stalked condition which 

 we have just seen to constitute 

 a merely temporary stage in 

 the life -history of Comattda 

 is, on the other hand, the per- 

 manent state of parts in all the 

 " Stone - lilies " and in most 

 other fossil Crinoidea, and in 

 a few living forms. Of the 

 living stalked Crinoids the 

 ones with which naturalists 

 have been longest acquainted 

 are the species of Pentacrinus, 

 from the seas of the West 

 Indie.s. Recently a number of 

 stalked Crinoids have been 

 obtained from great dejiths in 

 the sea, showing that these 

 ancient types still survive, 

 tliough in much diminished 

 iiundicrs. One of the most 

 interesting of tliese deep-sea 

 iti'iixi.i (fig. 67), which seems 

 to b.' distriliuted over the whole of the deeper jiortiona of the 



ir tilllrs 



■ W.wi 

 ml siz 



lie 

 .rth 



ilistriliuted 

 AUautic. 



little A7//:<)rv 



ver the whole of 



/.,/ 



