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ORDER III. ABRANCHIATA.* 



THESE are distinguished, as their name implies, 

 by the absence of all gills, externally : some of 

 them, as the Worms, seem to respire by the whole 

 surface of the skin, and others, as the Leeches, by 

 certain cavities within the body, communicating w r ith 

 the air through minute pores on the sides. These 

 two families are distinguished also by their respective 

 modes of progression ; the Worms moving by means 

 of minute bristles, and the Leeches, which are 

 smooth, by a sucker or disk at each extremity. 



Besides the preceding characters, the Earth-worms 

 (Lumbricus-f) are distinguished by a very lengthened 

 body of a cylindrical shape, divided by wrinkles 

 into very numerous rings, amounting in the common 

 species (L. Terrestris) to one hundred and twenty ; 

 the mouth is destitute of teeth : they have neither 

 tentacles nor eyes. The common Earth-worm may 

 be considered as an useful animal; perforating the 

 ground in every direction with numberless channels, 

 it lightens those clayey soils which otherwise would 

 adhere into impenetrable masses, and gives opportu- 

 nity for the rain to percolate into every part. To 

 no inconsiderable extent also they doubtless enrich 

 it with manure. White of Selborne observes, 



* A, without, and Irancliia, gills. f Their Latin name. 



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