192 THK AIF.CMANICAL FUNCTIONS. 



with the former. Here, instead of tlie retrencli- 

 ment of tlie appendages, we find them greatly de- 

 veloped, and amplified in every possible degree. 

 The rays of the Asterias become narrower, while 

 their length is at the same time increased ; the 

 vital organs, and also the tubular feet, are gradually 

 withdrawn from them, and retire within a central 

 disk, to which the slender rays, now bereft of feet, 

 become mere appendages. Such is the condition 

 of the Ophiura. (Fig. 92.) By the prolongation 

 and tapering of these rays to slender filaments, they 

 acquire a greater prehensile power, and twine with 

 ease round their prey. We next find their number 

 augmented ; it is at first doubled, then tripled, and 

 at length indefinitely augmented. They also be- 

 come branched, subdividing by simple bifurcations, 

 as in the Euryale palmiferum (Fig. 93) ; next into 

 minuter ramifications, as in the Caput Medusce, 

 where the thousands of filaments have the appear- 

 ance of a tangled web, which defies all attempts at 

 unravelling. 



The steps are but short from the Caput Medusae 

 to the Crmoidea, or lily-shaped tribe, (of which, 

 Fig. 94, representing the Pentacrinns europceus, is 

 an example) ; for they consist chiefly in the addi- 

 tion of a jointed stalk, which is made to proceed 

 downwards from the centre of the whole assemblage 

 of rays, and which is to serve as a common stem 

 for sustaining the whole mass ; while the branches 

 themselves are carried up, and folded inwards. 

 The lower joint of the foot-stalk is a little expanded, 

 in order to procure a more extensive base of support ; 

 and the whole structure thus presents a remarkable 

 resemblance to a liliaceous plant. 



