32 LUCANID^ A'SB TASSALID^. 



Examination of Hie various organs of tlic mouth shows as 

 little agreement as can be found in the shape of the antennae 

 or of the larva*. It is no doubt true, as maintained by 

 Lacordaire, that in general tlie two gi'oups agree in having 

 less freeh' movable lamellae in the antennal club than other 

 Lamellicornia. In certain Lucanid^ (e. g. Fignlus) the club 

 appears to be almost completely rigid, but there is very great 

 variation amongst the genera in this respect, and, in view 

 of the immense variety of structure occurring in the antennae 

 of the Lamellicornia, that group is quite comprehensive enough 

 to include the two families Lucanid^ and Passalid^. 



The later history of the Passalidje has been a peculiarly 

 unhappy one. The quinary system into which they were 

 remorselessly regimented by Kaup (' Monograph of the 

 Passalidae,' Berl. Ent. Zeit., 1871, supf)l.) demanded that no 

 genus should contain more than five si:)ecies and tliat every 

 five genera should constitute a distinct group. The 171 sjwcies 

 known to him required no less than 58 genera for their accom- 

 modation, leaving exactly 7 genera and 154 species still 

 undiscovered, to which he wisely refrained from giving names. 



The creation of generic and specific names on wholly inade- 

 quate groimds is often the direct cause of the creation of yet 

 more sui^erfiuous names b}' other workers for other specimens 

 that fail to conform to the flimsy definitions. Kauji's successor, 

 Kuwert, attempting to build a better structure without 

 relaying the foundations, instead of drastically reducing the 

 number of genera actually added 00 more. His monograph 

 of the family, ' Die Passaliden dichotomisch bearbeitet ' 

 (Nov. Zool., 1896-98), is lamentably uncritical and full of 

 errors. Later students of the group, F. H. Gravely (' A 

 Contribution towards the classification of the Passalida* of 

 the World,' Mem. Ind. Mus., vii, 191 S, p. 1) and Messrs. 

 Hincks and Dibb, who have comjiiled a catalogue of the 

 family (Coleopt. Cat., Passalidae 1935), altliough they have 

 raised the total of the species to almost 500, have reduced 

 tlie genera to much less than half, and still furtlier i-eductioTi 

 seems to he needed. 



This ])r()cess of reduction in the numi)er of genera is in 

 truth a natuial one in any large grouj) as the number of known 

 forms increases. In early days of systematic science, when 

 comparatively few forms were known, tlie gajis separating 

 them were many, and genera and larger divisions were therefore 

 easily defined. With the gradually increasing number of 

 known forms, these gaps become more and more filled and 

 many of them disappear entirely. Divisions which seemed 

 natuT-al c-ease to be so and genera must either be united or 

 have their limits aihitrarily fixed. If a formula can be found 

 for definitig iiitcMigihIy an arhitrary hoimdary, this may be' 



