468 GENERAL CHARACTERS OF STAR-FISH. CRINOIDEA. 



of great voracity. Like the Actiniae, they seem to be always 

 gaping, as it were, for food ; and to swallow whatever falls in 

 their way. The mouth is extremely dilatable, so that it can 

 admit large shell-fish and Crustacea, as well as small fishes, and 

 fragments of larger bodies which may be cast upon the shore. 

 Like the Sea- Anemone, they usually disgorge the indigestible 

 parts by the same orifice ; and they seem also possessed of the 

 power of partially everting their stomachs, or turning them inside- 

 out, so that the lining membrane projects through the mouth. 

 Indeed it is in this condition that they frequently lie in wait for 

 their prey ; the protruded portion being wrapped round the ob- 

 ject, and then drawn in. It seems to be by some means of this 

 kind that the Asterias are able to destroy and digest Oysters and 

 Mussels, without drawing their bodies from the shell. 



1107. In the OphiurcevrQ find a more distinct central disk 

 than in the Asteriae ; and to this the viscera are confined. It is 

 furnished with arms, which are sometimes simple or undivided 

 from one extremity to the other, and of a rounded tapering form, 

 like a serpent's tail, as in the genus Ophiura; whilst in other 

 genera, as the Euryale, they ramify minutely, dividing regularly 

 into branches, which .again subdivide, so as to form a most com- 

 plex series of appendages. These arms are all composed of 

 jointed plates, like those of the Asteria; and they are possessed 

 of spines or scales. The Ophiurce are much more active in their 

 habits than are the Asteriae. Their rays seem very flexible ; and 

 by the contraction of their envelope they may be moved in all 

 directions. Thus they are able to swim and to walk with con- 

 siderable facility ; as well as to exercise considerable power in 

 obtaining their prey. 



ORDER III. CRINO'lDEA. 



1 108. This interesting Order of Echinoderms, which was form- 

 erly much more abundantly represented, receives its name from 

 the lily -like form which several of its members present (Fig. 

 709). All of them, instead of moving freely where they will, 



