ECHINODERMS. 



41 



in this respect, for all over the exterior are numerous spines which in some 

 species are much longer than on the form here figured, being occasionally 

 two or three times as long as the diameter of the body itself. Still the 

 name Echinoderm is not literally 

 applicable to all, for in many forms 

 there are no spines on the skin, 

 and yet there can be no doubt of 

 their near relationship to the ur- 

 chin. None of the group possess 

 any great economic importance, 

 and yet there are many interest- 

 ing facts connected with them. 



First in order come the Crinoids, 

 a group now nearly extinct. In 

 the oldest rocks occur the remains, 



aetimes in enormous numbers, 

 of long, jointed columns, on the 

 summits of which may frequently 



found the remains of the rest 

 of the animal. The jointed stalk 

 frequently became broken up, and 

 these fossil joints were long known 

 as " St. Cuthbert's beads." When, FlG 

 however, the stalk remained entire 

 and retained the rest of the animal on its summit, it was known as a 

 stone-lily ; and the name was appropriate, for the whole often resembled 

 a flower more closely than even the living form figured in this connection. 

 For many years the living stalked crinoids were exceedingly rare ; only 

 one species was known (from the West Indies), and of this, up to 1856, 

 only seven specimens existed in all of the museums of the world. Now, 

 since the deep-sea dredge has explored the sea, both species and specimens 

 are much more numerous, and all of the large museums contain one or 

 more of them. 



For many years there was known in the seas of Europe a peculiar star- 

 fish, represented in the accompanying cut. From its color, and from the 

 pinnations on the long, curling arms, it had received the common name of 

 the rosy feather-star. There was hardly a suspicion but that it was what it 

 appeared to be until in 1836 Mr. J. V. Thompson showed that in its earlier 

 stage it was a veritable crinoid, living on a stalk and agreeing in all its 

 essential characters with the fossils so plentiful in the rocks. It had a 

 mouth in the centre of the arms, while around the place where it was 



42 



A living crinoid (Pentacrinus) , with the 

 region of the mouth on a larger scale. 



