EC HINODERM AT A. 
287 
e ternally hidden from the eyes of man, sleeps imder the heavy mass of 
^ater ; and yet man imagines that everything in Nature has been 
Seated for his use and for his glory. 
bf. Hupe records a somewhat curious observation in connection with 
spines, which serve as a means of defence to our Echinodermata. 
found a small mollusc, of the genus $ielifera, which had sought 
belter in Leixidaris imperictlis, an urchin, native of Australia ; in a 
' v °rd, the interior of one of these prickles had been hollowed and 
Charged so as to serve as a retreat for this improvised guest. 
^Vliat unexpected facts does the study of animals present ! Nature 
8,8 bestowed a protecting armour upon one little being ; another still 
Waller animal discovers this and places itself for shelter imder the 
Protection of these levelled bayonets ! Numerous anecdotes are told 
them. Thus : A man ignorantly put into his mouth one of these 
Matures, with all its prickles, and, being detected, thought himself, 
-bis pride, compelled to swallow it because he was being looked at ; 
'^ttiediately his mouth was full of blood. The next day he was in 
l' lc b a state of suffering that he could neither eat nor drink, and for a 
0IX S time his life could only be preserved by nourishing injections of 
0ll P> cream, and rice. 
ow let us see by what organic mechanism the urchin contrives 
' transport itself and walk. The tentacula, or suckers, are hollow 
to 
Usually, and, as we have said, are provided with small muscles. By 
1 all tl 
j. 7 » 
to any solid body, at the will of the animal, by means of their 
J 5 "“"J 7 J. 
influx of liquid which they inclose they become inflated through- 
° n ‘ b all them prickles, in such a manner that they can attach them- 
aelvr - 
tei 
% 
of 
its 
e ^ca 
^bers follow, but the animal is firmly fixed. If it wishes for change 
Place, the anterior filaments contract themselves, whilst the hinder 
° ,|r ' s loosen their hold, and the shell is carried forward. The sea- 
^ c bin can thus advance with ease, and even rapidity. During his 
j. °S r ession the suckers are only slightly aided by the spines. It can 
^ avel either ojt the back or stomach ; whatever their posture, they 
!lv<: always a certain number of prickles, which carry them, and 
!rt,| ina] suckers. Fredol, in “ Le Monde de les Mers,” thus explains 
“ Urchin's mode of progression : “ Let us imagine,” he says, “ one 
Ibese creatures to be at rest ; all its spines are immovable, and all 
filaments repose within the shell ; some of these involuntarily 
■Pe ; they extend themselves and feel the ground all round them ; 
