IO2 BY THE DEEP SEA. 



Within .we find a set of organs similar to those described in 

 connection with Five-fingers, much of the space being occupied 

 with the water-vascular system by which the enormous number 

 of sucker-feet are worked. The Urchin also possesses a great 

 number of pedicellarias which keep the upper parts of the huge 

 sphere clean, by passing any particles of dirt from one to the 

 other, until they are passed off altogether. The madrepori- 

 form plate is situate right at the summit of the edifice, near 

 the five eyes and the vent. As its specific name suggests, this 

 urchin is edible ; it is boiled like an egg. 



The Purple-tipped Urchin (Echinus miliaris} is depressed 

 in form, and its outline would represent an oval from which 

 one-fourth had been cut away, whilst E. esculentus would repre- 

 sent a circle from which about one-sixth had been abstracted. 

 The skin of E. esculentus^ when the spines are removed, is red- 

 dish; that of E. miliariS) a dusky greenish -grey. Miliaris 

 is common in rock-pools and about the rocks at low-water ; but 

 esculentus is found in deeper water, though, from the frequency 

 with which it is brought in by the crabbers for destruction, 

 rather than throw it overboard where they find it, and from its 

 empty house being rolled in by the waves, it is a fairly common 

 object of the shore. 



There is a rarer shore species, called the Purple Urchin 

 (Strongylocentrus lividus], which excavates circular holes in 

 the rocks large enough to house itself, spines and all. This is 

 more plentiful in Ireland than on the English coasts ; and it is 

 remarkable not only for its excavating propensities, but also 

 because it sheds its thick purple -spines annually, and produces 

 a new crop. 



Closely allied to the Sea-stars and Sea-urchins are the Sea- 

 cucumbers, of which we have a number of native species, 

 though many of them belong too exclusively to the deeper 

 waters to be mentioned here. Several of the genus Cucumaria, 

 however, may be met among the rocks, at low-water, on 

 our southern coasts. One of these is represented in the 



