DISTRIBUTION OF ORGANISMS. 



167 



are perhaps improperly ranked with other Radiata, 

 seeing that their character is so much superior. In 

 general highly organized, and enjoying free move- 

 ment at the bottom of the sea, these animals are 

 signally destructive. Admitted to be in their lower 

 forms intimately allied to the Polyps, they probably 

 start in some portion of that extensive order. One 

 of their earliest forms is the Encrinus or stone-lily, 

 a group of animals of which we have seen many 

 varieties flourishing in the early seas, but which are 

 now nearly extinct. The creature consisted of a 

 stomach and mouth, surrounded by long tentacles 

 or arms, placed upon the top of a stalk fixed to the 



FIG, 80. 



FIG. 79. 



Comatula rosacea (recent). 



Encrinites 



monilifor* 

 mis. 



sea-bottom, the whole being composed of numberless minute cal- 

 careous plates, connected by gelatinous substance. In more 

 advanced forms of the same order, (as the Comatula and the 

 extinct Marsupite), the body and arms desert the stalk, and 

 betake themselves to a free-swimming life ; but, as has been 

 elsewhere mentioned (page 134), the young comatula lives for 

 a time as an encrinus ; that is, upon a stalk. Seeing that the 



