Chap. 51.] 
YAEIOTTS KINDS OF CRABS. 
427 
while tlie sun is passing througli the sign of Cancer, the dead 
bodies of the crabs, which are lying thrown up on the shore, 
are transformed into serpents. 
To the same class^'^ also belongs the sea-urchin,^^ which has 
spines in place of feet ;^ its mode of moving along is to roll 
like a ball, hence it is that these animals are often found with 
their prickles rubbed off. Those among them which have the 
longest spines of all, are known by the name of echinometrse,^^ 
while at the same time their body is the very smallest. They 
are not all of them of the same glassy colour ; in the vicinity 
of Torone^ they are white, ®^ with very short spines. The eggs®'' 
of all of them are bitter, and are five in number ; the mouth 
is situate in the middle of the body, and faces the earth.^^ It is 
said that these creatures foreknow the approach of a storm at 
sea, and that they take up little stones with which they cover^^ 
themselves, and so provide a sort of ballast against their volu- 
bility, for they are very unwilling by rolling along to wear 
away their prickles. As soon as seafaring persons observe 
this, they at once moor their ship with several anchors. 
(32.) To the same genus^^ also belong both land and water^^ 
snails, which thrust the body forth from their abode, and 
extend or contract two horns, as it were. They are without 
®2 Of animals covered with a thin crust. 
^3 The se^-urchin, the herisson de mer of the French, and the Echinus 
of Linnaeus. 
Cuvier remarks, that it does not use the spines or prickles for this 
urpose, but that it moves by means of tentacules, which it projects from 
etween its prickles. 
The Echinus cidaris of Linnaeus; with a small body, and very long 
spines. The name, according to Hardouin, is from the Greek, meaning 
the " mother of the echini. 
86 See B. iv. c. 17. 
®^ The same, Cuvier says, with the Echinus spatagus of Linnaeus. 
^8 Not "ova," Cuvier says, but " ovaria" rather. Each urchin has five 
ovaria," arranged in the form of stars. They are supposed to be herma- 
phroditical, but there is considerable doubt on the subject. 
8^ The mouth of the sea-urchin, armed with five teeth, is generally turned 
to the ground, Cuvier says. 
Plutarch, in his Book " on the Instincts of Animals." Oppian, Halieut. 
B. ii. 1, 225, and JElian, Hist. Anim. B. vii. c. 44, all mention this. 
This idea probably arose from the fact of their being sometimes found 
with stones sticking between their spines or prickles. 
^ The thin-crusted animals. 
®2 Known to us as periwinkles. 
