38 LUCANID^. 



of an ancient phase. In well-developed specimens the 

 mandibles are more widely separated, the teeth foil to meet 

 or interlock, become suppressed or changed in their character. 

 In full-sized males the jaws are nearly alwaj-s symmetrical. 



The form of the cl\-peal process, yvhich lies between the 

 mandibles, varies according to the distance of these apart. 

 In some species, e. g. Dorcus antB:US, they are very widely 

 separated in the male and the clypeal process is correspondingly 

 wide. It is generally very short, but sometimes, as in the 

 genus Lucanus, may be produced in a downward direction so 

 that the mouth becomes vertical instead of horizontal. The 

 process may itself bear secondary processes. A remarkable 

 example of this is seen in Lucanus lunifer, which bears a 

 strange forked projection between the mandibles. 



The labrum is comi^letely united with the clypeus and never 

 plainly visible, as it is in the Passalid.^. The clypeal process 

 is therefore called by Gravely the cl^qjeo-labrum, the labrum 

 itself being the outwardly invisible roof of the mouth. 

 Equally immovable is the nientum, forming the floor. This is 

 highly chitinized and generally broad. It is commonly 

 difterent in male and female and may bear a thick clothing of 

 hair beneath in the former. To the mentum is attached the 

 ligula, which lies within the mouth and usually consists of two 

 lobes fringed with long hairs. The short labial palpi, attached 

 at its base, can be extruded or withdrawn. Also extrusible 

 are the maxillse, comjiletely covered by the mentum when at 

 rest, but w^ith the long maxillar}' palpi exjaosed. The maxillae 

 bear brushes of long hairs, which serve to suck up the liquids 

 which form the only nourishment of man}' of the adult insects. 

 The maxillae are not distinctly bilobed, as in the Passalid.e, 

 the imier lobe not being free, but there may be a small horny 

 hook at its anterior end. This is found in both sexes in 

 certain genera {Figulus, Nigidius, etc.), generally present in 

 females but not males of Dorcus, Cyclommatus and related 

 genera, and absent in both sexes of Lucanus, Calcodes, 

 jEgus, etc. 



The i)rothorax, as already mentioned, may differ greatly in 

 the two sexes of the same sj^ecies. It is generally rather short, 

 and in many males, but never in the other sex, maj' be much 

 smaller than the head. The base fits closely against the 

 bases of the elytra and may be sharply angular at each end or 

 curve gently round to the side. There is often an angulation 

 of the lateral margin, which may be sharpened into a strong 

 spine. By the obliteration of the hind angle this lateral angle 

 may come to form a secondary basal angle, as in Dorcus huddha, 

 etc. But there is also a tendency for a slight emargination to 

 occur at the side just behind the front angle, and to become 

 accentuated in such a wa}- as to produce a spiniform angle at 



