116 CLASSIFICATION OF INSECTS. 



the wings form a close reticulation or network by their inter- 

 lacement. The degree of metamorphosis is variable. 



Order IV. HYMEN OPTERA (Bee, Wasp, Saw-fly). In these, 

 the mouth is still furnished, as in the preceding, with prehensile 

 mandibles, but the other parts are so formed as to be rather 

 fitted for suction than for mastication ; the wings are all mem- 

 branous, but the nerves do not form such a minute reticulation 

 as in the preceding order; the metamorphosis is always complete. 



The four preceding orders, in which mandibles are always 

 distinctly present, form the group of MANDIBULATA; the four suc- 

 ceeding, in which the mandibles are wanting or are completely 

 changed in form, and in which the other parts are adapted for 

 suction, being converted into a more or less complete haustellium 

 or sucking- tube, are termed HAUSTELLATA. 



Order V. HOMOPTERA (Cicada, Lantern-fly). In this order, 

 the four wings are of the same consistence, and are rather firmer 

 than usual, being often somewhat parchmenty in texture ; when 

 folded, they incline at an angle, like the roof of a house. 



Order VI. HETEROPTERA (Bugs, Boat-flies). The consist- 

 ence of the two pairs of wings is here different, the anterior pair 

 of wings being of a horny or parchmenty consistence (though 

 generally tipped with membrane), whilst the posterior are simply 

 membranous ; when folded, they are horizontal, or but slightly 

 inclined, and sometimes lap over each other. 



Order VII. LEPIDOPTERA (Butterflies and Moths). These 

 have the mouth furnished with a long trunk, coiled in a spiral 

 when not in use ; the wings are all membranous, and are covered 

 with minute scales, having the appearance of fine dust, but 

 arranged with the most perfect regularity ; the metamorphosis 

 Js complete. 



Order VIII. DIPTERA (Gnats, Flies, fyc.) In these there are 

 but two wings ; the mouth is furnished with a sucking-tube ; and 

 the metamorphosis is complete, or nearly so. 



Division b. Insects undergoing metamorphosis, but destitute of 

 wings. This division includes but a single order. 



Order IX. APHANIPTERA (Flea, fyc.) In this group, also, 

 the mouth is formed for suction ; and the insects composing it are 

 parasitic, living upon the juices of other animals. 



