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triangular mouth, as well as the leech, with a pro- 

 jecting fleshy upper lip, but no lower one ; and 

 somewhat similar are these parts in the spider. 

 In the scorpion, on the contrary, and in insects 

 in general, it is a long process of the lower lip 

 which is usually called the tongue. In the buzz- 

 fly, hornet-fly, gnat, mosquito, house-fly, &c., as 

 well as in dipterous insects in general, the lips, 

 like those of the wared whelk, are prolonged 

 into a proboscis, containing a sucking-tube or 

 tongue, and sometimes several penetrating points 

 in addition. Insects are without proper salivary 

 glands ; but, somewhat analogous to these al- 

 though for a very different purpose are the 

 venom-bags of several tribes, as the centipede 

 and the spider ; in the latter of which there is 

 placed upon the bag a hollow tooth, which, press- 

 ing upon the bag in the act of penetrating their 

 prey, at once forces out a portion of the venom, 

 and conducts it into the wound. All kinds of 

 spiders appear to feed on animals alone, as upon 

 other insects and very small birds, as the hum- 

 ming bird ; and hence the advantage to them 

 of this apparatus. The story of the bite of one 

 kind of spider the tarantula producing in man 

 a kind of St. Vitus' dance, which is curable only 

 by music, is probably fabulous-; but, that it occa- 

 sions sometimes a very severe inflammation of 

 the skin, is abundantly certain; and that of the 

 centipede is not unfrequently fatal. It is upon 

 precisely the same principle that many plants, 

 as the common stinging-nettle, produce their 



