232 



THE MICROSCOPE AND ITS REVELATIONS. 



628. The Antenna, which are the two jointed appendages arising from 

 the upper part of the head of Insects (Fig. 423, Z> b), present a most 

 wonderful variety of conformation in the several tribes of Insects; often 

 differing considerably in the several species of one genus, and even in the 

 two sexes of the same species. Hence the characters which they afford 

 are extremely useful in classification; especially since their structure 

 must almost necessarily be in some way related to the habits and general 

 economy of the creatures to which they belong, although our imperfect 

 acquaintance with their function may prevent us from clearly discerning 

 this relation. Thus among the Coleoptera we find one large family, in- 

 cluding the Glow-worm, Fire-fly, Skip-jack, etc., distinguished by the 

 toothed or serrated form of the antennae, and hence called Serricornes; 

 in another, of which the Burying-beetle is the type, the antennae are ter- 

 minated by a club-shaped enlargement, so that these beetles are termed 



FIG. 426. 



FIG. 427. 



Minute structure of leaf -like expansions of An- 

 tenna of Melnlontha: A, their internal layer; B, 

 their superficial layer. 



Antenna of Melolontha (Cockchafer). 



Clavicornes; in another, again, of which the Hydrophilus or large Water- 

 beetle is an example, the antennae are never longer and are commonly 

 shorter than one of the pairs of palpi, whence the name of Palpicorne* 

 is given to this group; in the very large family that includes the Lucani 

 or Stag-beetles with the Scaralcei, of which the Cockchafer is the com- 

 monest example, the antennae terminate in a set of leaf -like appendages, 

 which are sometimes arranged like a fan or the leaves of an open book 

 (Fig. 426), are sometimes parallel to each other like the teeth of a comb, 

 and sometimes fold one over the other, thence giving the name Lamelli- 

 cornes; whilst another large family is distinguished by the appellation 

 Longicornes, from the great length of the antennae, which are at least as 

 long as the body, and often longer. Among the Lepidoptera, again, the 

 conformation of the antennae, frequently enables us at once to distin- 

 guish the group to which any specimen belongs. As every treatise on 

 Entomology contains figures and descriptions of the principal .types of 



