JAWS OF INSECTS. 



Ill 



For an account of the various modifications 

 which these parts receive in different tribes and 

 species, I must refer to works which treat pro- 

 fessedly of this branch of comparative anatomy. 

 I shall content myself with giving a single example 

 of the conversion of structure here alluded to, in 

 that of the rostrum, or proboscis of the Cimex ni- 

 gricornis. This insect belongs to the order He- 

 miptera, which has been usually characterised as 

 being destitute of both mandibles and jaws; and 

 as having, instead of these parts, an apparatus of 

 very different construction, designed to pierce the 



skin of animals and suck their 

 juices. But Savigny, on apply- 

 ing the principles of his theory, 

 has recognised, in the proboscis 

 of the Cimex, the existence of 

 all the constituent elements 

 which are found in the mouth 

 of insects formed for the masti- 

 cation of solid food. This pro- 

 boscis consists of four elongated 

 filaments, contained in a kind 

 of sheath : the filaments are re- 

 presented in Fig. 268, separated 

 to a little distance from each 

 other, in order that their re- 

 spective origins may be dis- 

 tinctly seen ; the one set (q), 

 being prolongations of the man- 

 dibles (j), and the other set (p) 

 being, in like manner, prolongations of the maxillae 

 (m). Between these filaments, and near their com- 

 mencement, is seen a pointed cartilaginous body 



