THE SEA-HARE. 285 
meet around the stem, thus tightly grasping it as if enclosed in 
a tube. While progressing, the fore part is poked forward as a 
narrow neck furnished with two pair of tentacles, one pair of 
which, standing erect and being formed of thin lamin, ben! 
round so as to bring the edges nearly into contact, look like the 
ears of the timid quadruped, from which the Aplysia has derived 
its common name. The colour is a dark-brownish purple studded 
with rings and spots of white. On being disturbed, the sea-hare 
pours out from beneath the mantle-lobes a copious fluid of the 
richest purple hue, which however quickly fades, and is of no 
value in the arts. 
More than forty species of Aplysiz are known, most of them 
inhabitants of the warmer seas. The acrid humour exuded by 
the depilatory aplysia, or Aplysia depilans, of the Mediterranean 
is still supposed by the Italian fishermen to occasion the loss of 
the hair, and was used by the ancient Romans in the composi- 
tion of their venomous potions—though it is by no means 
poisonous. Such.are the prejudices resulting from the pro- 
pensity of man to associate evil qualities with an unprepossessing 
appearance. 
To the Cyclobranchiate order belong the Limpets and the 
Chitons. The latter, which are the only multivalve shells among 
the Gasteropods, are spread in more than two hundred species 
over every shore from Iceland to the Indies, but they are 
particularly abundant on the coasts of Peru and Chili. Some of 
the smaller species inhabit our coasts, where they may be found 
adhering to stones near low water mark. They 
are coated with eight transverse shelly plates, 
folding over each other at their edges like the 
plates of ancient armour, and inserted into a 
tough marginal band, so as to form a complete 
shield to the animal. Thus encased in coat of 
mail, the chitors have the power of baffling 
the voracity of their enemies by rolling themselves up into a 
ball like the wood-louse or the armadillo: they are also able to 
cling with such tenacity to the rock that it is difficult to detach 
them without tearing them to pieces. The Limpets, or Patelle, 
likewise attach their shield-like shell so firmly to a hard body 
that it requires the introduction of a knife between the shell and 
the stone to detach them. It has been calculated that the 
Chiton squamosus. 
