P A SSALI DAI. — LTJCANIDiE. 207 



to feed without parental assistance. Both larval and adult 

 Passalid.e stridulate loudly and constantly, and in these organized 

 communities it seems to be undeniable that the vocal powers 

 serve the purpose of intercommunication. Dr. Ohaus records an 

 interesting episode which may be quoted as a proof of this. 



" Breaking up a log in search of larvae of another group he 

 disturbed a community of PassalidvE consisting of the parents 

 and six larvae. Not wishing to keep them, he put them on the 

 ground and went on with his search. Having finished this he 

 was preparing to leave when another log near by attracted his 

 attention, and he turned it over. Beneath it were the two beetles 

 and four of their brood, while the other two were making for the 

 same shelter as fast as intervening obstacles would allow. The 

 chirping of the whole party had all the time been audible, and my 

 friend is convinced that the larvae were guided by this means into 

 safety, exactly as chickens are by the clucking of their mother. 

 As they are without trace of eyes, it is difficult to resist this 

 conclusion." 



Dr. Ohaus speaks above of the parent beetles triturating the 

 wood for their offspring ; the mandibles with which they do this 

 are strong, and are provided with a molar tooth at the base and 

 another movable tooth just above this. The action of this tooth 

 has been observed by Zimmermann and others; it is placed close 

 to the stationary tooth, which forms its fulcrum, and this arrange- 

 ment helps the insect in the division of the wood into minute 

 fragments. The muscles of the movable tooth appear to be 

 situated in the substance of the mandibles (v. Lacordaire, Gren. 

 Coleopt. iii, pp. 44, 45). 



In the Passalid.e the males and females are identical externally, 

 differing entirely in this respect from the Lucanidje. 



Family 101. LUCANID.E. 



Convex or moderately convex, but not cylindrical, insects ; antennce 

 with a pectinate club, the joints of tvhivJi cannot be applied to one 

 another, elbowed or geniculate ; labrum nearly always connate with, 

 the clypeus ; mentum entire; mandibles very strongly developed in 

 the nudes; maxilla? with two lobes; anterior coxal cavities closed 

 behind; intermediate coxa? transverse ; mesosternum short, meta- 

 sternum large ; elytra not longitudinally sulcate, entirely covering 

 abdomen; tarsi five-jointed, the last joint elongate. 



The LucANiuiE, or Stag-Beetles, are among the best known of 

 the Coleoptera by reason of the great development of the mandibles 

 in the males, these being usually regarded as horns by the ordinary 

 observer. In some of the exotic species these organs are nearly 



