INSECTS. 8 1 



and bees they form the instruments with which these insects build 

 their admirable edifices, and, to use the words of a popular author, 

 supply the place of trowels, spades, pickaxes, saws, scissors, and 

 knives, as the necessity of the case may require. Beneath the 

 mandibles is situated another pair of jaws, c, of similar construc- 

 tion, but generally smaller, and less powerful : these are called 

 the maxilla. The lower lip, or labium, which closes the mouth 

 inferiorly, consists of two distinct portions, usually described as 

 separate organs : the chin, mcntiim, that really forms the inferior 

 border of the mouth, and a membranaceous or somewhat fleshy 

 organ, reposing upon the chin internally, and called the tongue 

 (lingua). All these parts enter into the composition of the per- 

 fect mouth of an insect, and from the numerous varieties that 

 occur in their shape and proportions, they become important 

 guides to the entomologist in the determination and distribution 

 of species. 



The organs of sense in insects are distinct and well developed, 

 though we cannot in all cases precisely determine the sensations 

 of which they are the channels. Thus, the two jointed members 

 called antenna:, that project from the head, are believed by some 

 to be organs of touch, by others to convey delicate perceptions 

 unknown to us, and by the generality of entomologists are con- 

 sidered to be in some way sensible to sound. They are composed 

 of a varying number of rings, sometimes as many as thirty, set 

 in succession ; the whole constituting a tube, and enclosing nerves, 

 muscles, and air-pipes. Their form is exceedingly varied ; and 

 in many instances they are ornamented with feather-like beards, 

 or curiously sculptured, so that they afford useful characters for 

 the identification of the multitudinous genera comprised in this 

 Class. 



The eyes of insects present some interesting peculiarities of 

 structure, indicative, no doubt, of corresponding diversities in the 

 sense of vision, of which we must ever remain ignorant. Two 

 distinct kinds of eyes are possessed by these animals, both kinds 

 being present in the majority of species. If we examine the head 

 of a bee, for example, we find a large convexity on each side, 

 which a magnifying glass discovers to be composed of an immense 

 number of facets, and on the summit of the head, between these, 

 we see three shining points, resembling minute gems, set in a 

 triangular form. The former are termed compound, the latter 

 simple eyes. The simple eyes consist of a glassy lens, behind 

 which a nervous thread is spread out, forming a retina, or net- 



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