LUCANIDAE. 119 



Fam. XXXI.— l U C A N I D A E . 



Mentum large, corneous, quadrate, rarely (Passalus) deeply 

 emarginate; ligula usually placed behind the mentum. 



Maxillae usually covered, with two lobes, the inner one 

 usually, the outer one sometimes, with a fixed corneous 

 terminal hook. 



Mandibles frequently very large. 



Labrum frequently connate with the epistoma; clypeal 

 suture wanting. 



Antennas inserted under the margin of the front, before 

 the eyes, usually geniculate, 10-jointed ; the first joint very 

 long in the first tribe, moderate in the second; the outer ones 

 prolonged internally, forming a pectinate club, the joints of 

 which cannot be brought closely together. 



Prothorax with the side pieces not separate; coxal cavities 

 separated by the prosternum, transverse, closed behind. 



Mesosternum short, separating the coxae; side pieces large, 

 diagonally divided; epimera attaining the coxae. 



Metasternum large, closely connate with the mesosternum 

 in front, receiving the apex of the first ventral segment in a 

 minute emargination behind; side pieces narrow; epimera 

 nearly concealed by the elytra. 



Elytra rounded at tip, covering the abdomen. 



Abdomen with five free ventral segments; the sixth (in- 

 ternal) slightly prominent in Platycerus ; spiracles situated 

 in the membrane between ventral and dorsal segments, but 

 different in position in the two tribes; in Lucanini they are 

 at the bottom of the lateral concavity of the dorsal surface 

 of the abdomen ; in Passalini they are situated on the crest 

 of the margin. 



Legs fossorial ; anterior coxae large, transverse, not promi- 

 nent, without trochantins; middle coxae usually transverse, 

 sometimes nearly rounded; posterior coxae transverse, flat; 

 trochanters not prominent internally; anterior tibiae more or 

 less toothed externally, frequently palmate, with one terminal 

 spur; middle and posterior tibiae with two external teeth, 

 terminal dilatation, and two spurs; tarsi slender, 5-jointed, 

 last joint long; claws simple, with a short intermediate ony- 

 chium bearing two bristles. 



The insects of this family live on the juices of decomposing 

 wood, and are very closely allied to the Scarahaeidae ; the prin- 



