LEECHES. 



169 



door after them, a small round richly-coloured lid, exactly fit- 

 ting the orifice, and hermetically closing it against all intruders. 



The tubicular annelides (such as the terebellse, serpulaB, and 

 sabella}) have the greatest resemblance in their mode of life 

 with the sedentary polypes, the flustrse, and the barnacles ; for all 

 these animals, firmly linked to the spot on which they live, de- 

 pend for their food upon the prey which the sea, their bounteous 

 mother, wafts within their grasp, and all, at the approach 

 of danger, shrink within the hollow of their shells or cells. 

 Yet how different is their internal structure, as they not only 

 belong to different families of one class, but even to totally dif- 

 ferent classes of animals ! Thus we find a prodigal multiplicity 

 of form in creatures, whose sensations and enjoyments seem to 

 be entirely on a level, for it has been the Creator's will that the 

 beauteous variety of our flower-beds should adorn the sub- 

 marine gardens of the crystal deep. 



The sweet water of the ponds and rivulets is far less abundant 

 in annelides than the briny sea. Here the small naides glide 

 swiftly about, by means of their long bristly feet, or attach 

 themselves to aquatic plants ; here also is the seat of the water- 

 leeches, a peculiar genus of worms, provided 

 with a sucker at both ends of the body, serving 

 them both for locomotion and for attaching 

 themselves to their prey. 



The mouth, situated in the middle of the 

 cavity of the anterior sucker, is as admirable a 

 piece of mechanism as that of the sea-urchin. 

 Three jaws are disposed around it in such a man- 

 ner, that theiredges, forming an obtuse angle, 

 meet in the centre like the radii of a circle. 

 Each jaw has two rows of minute teeth at its 

 edge, so as to resemble a small saw, and is im- 

 bedded at its base in a layer of muscle, by the 

 action of which it is worked in such a manner as 

 to cut into the skin and thus the well-known 

 triradiate form of the leech-bite is occasioned, 

 character of the wound is very favourable to the flow of blood, 

 which is still further encouraged by the action of the sucker. 



Armed with a weapon so beautifully adapted to their wants, 

 the leeches not only attack the frogs and fishes, on whose fluids 



Leeches (Hirudo 

 mecticmalis.) 



The lacerated 



