A Contribution towards the Revision of the 



Passalidae of the World. 



BY 



F. H. GRAVELY, D.Sc, 



Assistant Superintendent, Zoological Survey of India. 



(With Plate I.) 



WHEN preparing my "Account of the Oriental Passalidae" (1914c) the Jack of a 

 representative collection of American and African forms prevented me from 

 considering the relationship to other groups, borne by the Indo-Australian groups to which 

 the Oriental forms belong. Shortly after the publication of that paper, however, the 

 Passalidae collected by Mynheer J. R. H. N. Van de Poll were offered for sale. These were 

 bought by the Trustees of the Indian Museum, who thereby added a particularly fine set of 

 Indo-Australian species to their collection, together with much material for comparison 

 from America and Africa. My thanks are due to them for the encouragement which they 

 have thus given me to extend my investigations, so that they may include a study of the 

 classification of the whole family. 



I have further to thank Mr. G. J. Arrow for assistance in various forms, including the 

 loan of specimens from the British Museum ; Mr. C. Holman-Hunt for material from the Malay 

 Peninsula ; M. R. Vitalis de Salvaza for material from French Indo-China ; Mr. C. F. Baker 

 for material from the Philippines ; and M. Guy Babault and Mr. G. E. Bryant for material 



from various localities. 



Morphology of the Head. 



The study of a general collection of Passalidae, from parts of the world other than the 

 Oriental Region, at once throws light on the question of the morphology of the anterior part 

 of the head, a question which seemed most difficult before. It confirms as true for most 

 species of Passalidae the suggestion, made on p. 337 of my " Account of the Oriental 

 Passalidae," that " the whole of the upper surface of the anterior part of the head between 

 the supra-orbital ridges and in front of the frontal ridges is frons, the whole of the clypeus 

 being doubled beneath this out of sight ; " but it shows that this is not true of all species, 

 and that the groove which I supposed to represent the suture between the clypeus and 

 frons is probably situated beyond the lateral extremities of the former plate. 



The most primitive surviving forms of Passalidae appear to be included in the genera 

 Oileoides and Popilius, as these are defined below ; and Oileoides subrecticornis (see fig. i, 1 

 on next page) may conveniently be taken as an example of them. 



In this species the clypeus is not hidden, but is exposed as an extensive transverse plate 

 above the labrum. The labrum is attached by a well developed membrane, which extends 

 beneath it to the lower posterior margin of the clypeus, and not to its anterior margin. 



B 



