CH. XXI.] VARIOUS SPECIES OF CRABS. 281 



fleas which had been kept under water for twenty- 

 two hours, had revived on being taken out ; even 

 several females had remained unhurt when immersed 

 for eleven hours. 



The inhabitants of Dalecarlia place the skins of 

 hares in their apartments, in which the fleas willingly 

 take refuge, so that they are easily destroyed by the 

 immersion of the skin in hot water. But in this, as 

 in the case of other similar plagues, cleanliness is 

 the best remedy. 



CHAPTER XXI. 



THE NATURAL HISTORY OF VARIOUS SPECIES OF CRABS, AND 

 OTHER CRUSTACEOUS ANIMALS. 



History of the Lobster, the mode of casting its Skin, its Parasite 

 History of the Land-crab History of the Hermit-crab History 

 of the Pea-crab. 



THE crab, lobster, shrimp, prawn, and numerous 

 other species of aquatic animals, although regarded 

 by Linnaeus as belonging to the class of insects, 

 have been established by Cuvier, from a compara- 

 tive examination of their peculiarities of respiration, 

 circulation, &c., with those of the true insects, into 

 a distinct class, to which, from the hardness of the 

 crust or covering of their bodies, the name of Crus- 

 tacea has been applied. Still these animals, as well 

 as the spider, the scorpion, the centipede, and many 

 others, agree with the insects not only in the num- 

 ber of their legs, which are composed of several 

 joints, but also in the articulated structure of the 

 body ; hence the whole of these animals (insects we 

 can scarcely call them) have been again brought to- 

 gether, constituting the sub-kingdom Annulosa or 

 Articulata of modern authors. 



Aa2 F 



