191 8.J F. H. Gravely: Passalidae of the World. 11 



the record " Dar-es-Salaam " and the other " S. Catherina, S. 0. Brazil (Staudinger)." If 

 these records are correct, and the species to which they refer really do occur both in America 

 and in Africa or Madagascar, the occurrence in America of genera belonging to the group 

 typical of Africa would be very natural. But in the absence of direct personal evidence by 

 a collector I find it easier to believe them to be due to mistakes in labelling, numerous 

 though they are. The position of Mitorhinus and Stephanocephalus therefore requires 

 special consideration. 



Judging from Kaup's figure (1871, pi. vi, fig. 3) Passalus punctifrons, Dejean, the type 

 of the genus Mitrorhinus, would seem to be from America and to belong in all probability, 

 to the genus Passalus as this is defined below ; but Kaup identifies the species with 

 Percheron's Passalus cayor, a species the type of which is recorded as coming either from 

 Senegal or from Brazil. As Percheron's figure (1835, pi. v, fig. 2) shows this to be an insect 

 of the African type, the former is doubtless the correct locality. There can, I think, be little 

 doubt that cayor belongs in reality to the African genus Pentalobus ; and I suspect that 

 both Kaup and Kuwert have coafused prolongations of the anterior angles of the head 

 with the tubercles on the inner side of these angles characteristic of African forms. 

 Probably this has also been the case with the genus Stephanocephalus, the only species 

 figured, Percheron's Passalus hostilis (1 841, pi. lxxvii, fig. 4), whose locality was not known 

 to its author, being in all probability African, although Kaup and Kuwert have applied the 

 name to an American species, and have placed other American species in the same genus 

 with it. For the present, then, the form of the anterior margin of the head may be 

 regarded as separating American from Ethiopian groups ; but further evidence on the point 

 is much to be desired, especially as the aberrant genus Ptichopus is to some extent 

 transitional between the two. 1 



Another character by which the American and Ethiopian groups may be separated is 

 afforded by the posterior plate of the prosternum. In the former this is usually more or 

 less narrowed behind, and is often pointed ; whereas in the latter it is always more or less 

 parallel sided and broadly truncate. This plate has the African character in most species 

 of the American genus Paxillus, but I know of no other exceptions to the rule, although the 

 distinction is not equally well marked in all species. 



The Ethiopian genera fall conveniently into a single subfamily Solenocyclinae. The 

 American genera, on the other hand, fall into three groups, each in my opinion of sufficient 

 size and distinctness for recognition as a separate sub-family. 



The first of these, to which the name Pseudacanthinae may be given, is distinguished 

 chiefly by the presence of a well marked clypeo-frontal suture. Traces of this suture are 

 found also in the species described below under the name Chondrocephalus quinquecornuius, 

 and it is more or less complete in V index agnoscendus. The former of these species may be 

 regarded as in this character transitional between the two most primitive genera of the 

 Pseudacanthinae and Passalinae respectively ; and the latter agrees in every other character 

 with the Passaline genus Vindex and not with any Pseudacanthine genus. In spite of these 

 exceptions the presence of the suture in question remains the most distinctive single 



1 See also below, p. 13, footnote l : 



C2 



