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 laminae, bent 

 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 Aplysiae 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 Eomans 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 



,, rim- Chiton squamosus. 



mail, the chitons 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 

 clinw with such tenacity to the rock that it is difficult to detach 

 them without tearing them to pieces. The Limpets, or Patellae, 

 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 



