1918.] 



F. H. Gravely : Passalidae of the World. 



123 



The third and last line of descent from Mastochilus is found in the genera 

 Pseudepisphenus and Tarquinius, two extremely rare forms known only from New Guinea, 

 Their affinities have already been fully discussed elsewhere (Gravely, 1924c, 328-329). 



The Leptaulacinae are centred in the Malayan Sub-Region, whence several have spread 

 westwards and eastwards to the Indo-Chinese Sub-Region and Celebes respectively. The two 

 dominant species, L. bicolor and L. dentatus, have spread beyond these limits into the Indian 

 Peninsula and Ceylon in the west, and into the Moluccas, New Guinea, and possibly even 

 Australia in the east. Isolated species have arisen in several of the islands or island groups 

 of both the eastern and western parts of the archipelago. The number of distinct species 

 appears, however, to be small and the more widely distributed species especially are 

 extremely variable and often difficult to distinguish from one another. They are also 

 extremely abundant. This probably indicates that the subfamily is of relatively recent 

 origin and that it has not yet reached a condition of equilibrium. 



The importance of Palk Strait, the Gangetic Plain, the China Sea and Isthmus of Kra 

 (together), the Straits of Macassar and Torres Strait in the distribution of the MacroliDinae 

 has already been pointed out (Gravely, 1914c, p. 338). The further study of the Passalidae 

 of the Australian Region shows that the Molucca and Gilolo Straits are of no less 

 importance and, indeed, that to the former belongs the special importance which I 

 previously attached to the Straits of Macassar, the fauna of Celebes being even more 

 unlike that of the Australian Region than it is unlike that of the Oriental Region. 



The Passalids hitherto recorded from Celebes are as follows i 1 — 



foveicollis, 



Comacupes foveicollis subsp. minor 

 Aulacocyclus celebens-is 



Macrolinus sulciperfectus 



., duivenbodei 

 ,, urns 



Aceraius laevicollis 



Plesthenus spp. 



Trichostigmus ursulus 



Leptaulax planus . . 

 ,, bicolor . . 

 ,, cyclotaenius 

 dentatus 



("Genus otherwise purely Oriental ; C. 

 I s. str., confined to Borneo. 

 Endemic. Genus Indo-Australian. 

 ( Endemic. Belongs to the group of Macrolinus other- 

 ( wise known only from the Malayan Subregion. 



'These two constitute a group which is endemic. 



A Malayan species. The genus is so definitely 

 Oriental that I am inclined to doubt this record. 



Endemic. Allied to the Oriental Pelopides. 

 (Endemic. The only other known species of the 

 (. genus is Oriental. 



/ Oriental species which appear to be extending their 

 I range. One at least has reached New Guinea 

 \ and possibly Australia. 



Although a large proportion of these species are endemic, and it is doubtful whether 

 either of the two most characteristic asymmetrical Oriental genera, Aceraius and Pelopides, 

 occur in Celebes at all, it will be seen that every species known from Celebes is related to 

 species which are essentially Oriental, although some have established themselves in the 



Australian Region also. 



1 Concerning Kuwert's record of " Pelops " impressiccllis see above, p. 107, footnote 2. 



R 2 



