132 COMPARATIVE ANATOMY AND PHYSIOLOGY. 



become of considerable length when the Lepidopteron 

 feeds on the honey of plants, such as orchids, in 

 which the nectaries are at a considerable distance 

 from the outer edges of the flowers ; in, for example, 

 Amphonyx, one of the Sphingidse, the proboscis is 

 nine and a quarter inches long, or about three times 

 the length of the animal's body. In some Lepidoptera 

 the proboscis is enlarged to pierce vegetable tissues, 

 and, as in the orange-sucking 

 Ophideres, it has externally the 

 form and function of a bayonet- 

 shaped saw (F. Darwin). 



In the blood- or juice-sucking 

 Hemiptera (bugs, aphides) not 

 only the mandibles but also 

 the first pair of maxillae are re- 

 duced to fine setiform processes, 

 vvhich, being moved by muscles, 

 are enabled to serve as stabbing 

 organs ; they are ensheathed in 

 the elongated labium (rostrum) 

 the sides of which curve up- 

 wards in such a way as to 

 produce a sucking-tube (Fig. 61). 

 In the Diptera (or flies 

 and fleas), what were bristles in 

 the bug now form sharp, cut- 

 ting, lance c-like organs, and the 

 second pair of maxillse again 

 form the suctorial tube ; in some 

 cases (Pangonia) the proboscis 

 is more than twice as long as the body. 



Allied to various orders of insects are forms which, 

 in correlation with their modes of life, have their 

 gnathites still more considerably altered from the Or- 

 thopterous type ; thus, among the white ants (Termi- 

 tidse) the mandibles are functional in the so-called 



Fig. 61. Mouth Orgaii of 

 Nepa. 



md, Mandible ; mx, first pair 

 of maxilla; ma/, second 

 pair (labium); li, ligula. 

 (After Savigny.) 



