ANNELIDA TERRICOLA. 



breathe by means of branchiae, which are sometimes within 

 and sometimes without their bodies. They have no limbs, 

 but a great number of rings, each of which is furnished with 

 little bristles or spines for the purpose of locomotion. They 

 emit through certain pores a slimy fluid, which lubricates their 

 bodies and thus gives them an easier passage through the 

 earth, which they traverse in every direction. They feed upon 

 roots, woody fibres, and the remains of animal and vegetable 

 matter.. They swallow earth, also, in considerable quantity, 

 but this is probably on account of the animal or vegetable 

 matter which it may contain. When cut through the middle, 

 each portion becomes a distinct individual. 



The appearance of earth-worms is familiar to all, and in 

 conformity with their habits, their entire structure is adapted 

 to a subterranean existence, and their bodies so organized as 

 to enable them to burrow with facility through the dense and 

 unyielding materials in which they are usually found. Who- 

 ever has attentively watched the operations of an earth-worm 

 when busied in burying itself in the earth, must have been 

 struck with the seeming disproportion between the laborious 

 employment in which it is perpetually engaged, and the means 

 provided for enabling it to overcome difficulties apparently 

 insurmountable by any animal, unless provided with limbs of 

 extraordinary construction, and possessed of enormous mus- 

 cular power. In the mole and burrowing cricket at once are 

 recognized, in the immense development of the anterior legs, 

 a provision for digging admirably adapted to their subterra- 

 nean habits, and calculated to throw aside with facility the 

 earth through which they work their way ; but in the worms 

 under consideration, deprived as they appear to be of all exter- 

 nal members, feeble and sluggish even to a proverb, where is 

 to be found that mechanism which enables them to perforate 

 the surface of the ground, and to make for themselves, in the 

 hard and trodden mould, the pathways which they traverse 

 with such astonishing facility and quickness ? 



The structure of the outer fleshy integument of the earth- 

 worm resembles, in every respect, that of the leech (No. 17), 

 both in the annular arrangement apparent externally and the 

 disposition of the muscular strata. The suctorial discs, how- 

 ever, which in the leech formed such important instruments 

 of progression, are here totally wanting; and the annular 

 segments of the body, as they approach the anterior extremity, 



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