20 6 



] i TROnUCTlOX. 



The larvae of the Passalidjs appear to be very remarkable 

 both as regards their structure and their life-history. They 

 are more slender than the larvae of the Lucanidje, and have the 

 surface of the segments smoother, the head also being much 

 smaller. The chief peculiarity, however, lies in the legs. The 

 first and second pairs are comparatively long, but the posterior 

 pair is rudimentary, consisting of a very short coxa and a tro- 

 chanter about six times as long as this. The latter is modified 

 as a plectrum, which is arranged so as to strike or scratch a 

 istridulating area on the coxae of the second pair of legs ; occa- 

 sionally it is furnished with claws or digits, but more often it is 

 simple. 



These larvae differ also_from those of the Lucajstidje in the forma- 

 tion of the anal opening, which is transverse, with the upper lips 

 longitudinally split ; in this they approach certain of the Scara- 

 b.eidve. Asa matter of fact the Passalid^e, as pointed out by 

 Dr. Sharp, are more closely allied to the ScARAB^m^ than to the 

 Lucanid.e ; their nearest allies appear to be the Trogin.e and 

 (xEOTRUpin.e, which are probably the most ancient of the 

 Lamellicorjvia . 



The Passalld^e appear to have reached a higher pitch of family 

 organization than is found elsewhere among the Coleoptera. The 

 following account of the observations of Dr. Ohaus, quoted from 

 Mr. Arrow's paper before referred to (Trans. Ent. Soc. Loncl. 

 1904, p. 734) will serve to prove this : — 



" Having had considerable success in rearing the larvae of the 

 Lamellicornia, Dr. Ohaus tried to re ar those of Passalid^e in 

 the same w ay, many species being very common in the neighbour- 

 hood of Petropolis ; but to his surprise they invariably died in a 

 few day*. Determined to discover the reason of his failure, he 

 devoted himself for a time to the investigation of their natural 

 conditions of life, and soon observed that when a rotting trunk 

 contained tunnels inhabited by the larvae, a pair of adult beetles 

 was invariably to be found at the end of each tunnel, each pair 

 accompanied by from two to seven young ones. Transferring the 

 entire family to his breeding-cage, he found that they then fared 

 perfectly well. If individuals from different places were put 

 together they refused to settle down, and soon died or killed each 

 other, but by keeping each family by itself he had no difficulty in 

 following out their history. The adults were usually occupied in 

 disintegrating the wood at the far end of the burrow and chewing 

 it into a soft condition ready for the larvae, the condition of whose 

 jaws seems to render them incapable of procuring their own food. 

 Even when kept apart from their parents and the material pre- 

 pared by the latter supplied to them, they did not prosper, and 

 Dr. Ohaus considers it probable that a digestive secretion is mixed 

 with it before it is o-iven to them. The beetles devote constant 

 attention to their offspring from the time they leave the egg until 

 full maturity is reached, for even after the young beetle has 

 assumed its final shape the jaws are for some time too soft for it 



