288 
THE OCEAN WORLD. 
of 
suckers, with which they attach themselves. In certain circumstances 
the animal walks by turning upon itself, like a wheel in motion.” 
Nothing is more curious than to see a sea-urchin walk upon smooth 
sand. But for the colour, it might be mistaken for a chestnut with 
its bristling envelopes, the spines serving as feet to put the little round 
prickly mass in motion. They have even been observed to for® 
themselves into a ball, and roll along like a globular fagot of prickle® 1 
One of the most singular organs 
the sea-urchin is its mouth. It 13 
monstrous. Placed underneath th* 
body, it occupies the centre of a sod 
space invested with a thick resistive 
membrane : it opens and shuts ince®' 
santlv, showing five sharp teeth (F 1 # - 
115), projecting from the surface, tb e 
edges meeting at a point, as repr & 
Fig. 115. Buccal armature of Echinus lividus. 
sented here, supported and protect 
fed 
of 
by a very complicated framework, which has received the name 
Aristotle’s Lantern (Pig. 116). Fig. 115 represents Echinus 
in its normal state ; th® 
other shows the ® a ®^ 
catory organs, that is 
say, Aristotle’s Laidcr® 
To give the reader ® 
more complete idea ofth® 
buccal organ in the 
urchin, let him glance ® 
ono from the souther 11 
seas, Clypeaster rosac 
represented in Pig- ’ 
Fig. 116 . Masticating apparatus of Echinus lividus. Outline of the en 
animal, the buccal apP 1 * 
ratus being placed under the shell, which has been broken in Fig- ^ ’ 
so as to lay this organ bare. ^ 
The shape of the Clypeaster rosaceus is oval, straighter in fr 011 ’ 
and thick and rounded at the edges. It is 
more common and ®° r ® 
ed 
largely distributed than any other living species, and it is snppF 
with four or six ambulacra, or feet. 
