322 Mr. 0. J. Arrow on a Contrihution to the 



tootli. In all other respects the genus agrees with 

 raitodon, the front tibios have several secondary denticles 

 in addition to the three strong teeth, the hind tibiie are 

 truncated and setose and the mandibles are deeply notched 

 externally. This definition (which is not materially 

 diti'erent from that of Lacordaire), although it fits the 

 African and Madagascan species, excludes most of the 

 Asiatic ones at present assigned to Heteronych.u><. These 

 are H. 7norator and inccufi, ¥.,javanus and ^?a?^^;6'r, Burin., 

 swtplex, Waterh., annulafns and poroiiycjiis, Bates, Lans- 

 bcrgi, Schauf., dcscrti, lleyd., and hidcntidits, cribrdteU'us, 

 cicrtukcs, intcvrujifAis, monodou, pu7ictolineatits and suma- 

 trensis, Fairm. 



In addition to the above ff. criho'utellus, Fairm., another 

 species was described from Egypt by the same author 

 imder the same name and in the same year. This M. 

 Bedel has already found to be a synonym of Pcntodon 

 syriacus, Kraatz, and H. hidcntulus he has rightly referred 

 to the same genus. H. deserti, Heyd., may also be a 

 species oi Fentodon. It is not a Hetcronychus. The Oriental 

 H. cnhrakllus is one of a group of species in which 

 the pronotum is distinctly punctured and sometimes 

 slightly impressed in front, and in which the front tarsi 

 are not thickened ia the male, and for these it is necessary 

 that a new genus should be formed. It may be defined as 

 follows : — 



Alissonotum, n. gen. 



Mandibles strongly notched externully. Clypens attenuated and 

 bidentate at the end, bearing behind a tranHver.se bi-tuberculate 

 carina. Pronotum distinctly punctured, sometimes slightly impressed 

 at the middle in front, not clo.sely fringed at the sides. Front 

 tibia' 3-dentate, with minute secondary denticles. Front tarsi and 

 claws not thickened in the male. Propygidiura bearing two 

 microscopic stridulating files. 



Only the last feature and the strongly striated elytra 

 clearly distinguish this genus from Pcntodon. In that 

 there are sometimes traces of a double series of ridges 

 upon the propygidium but the files are always very 

 coarse and imperfect and the ridges do not nearly reach 

 the hinder margin of the segment. The recognised species 

 of Pcntodon are very homogeneous in size and form and are 

 essentially Palsearctic in distribution, whereas the present 



