1918.] 



F. H. Gravely : Passalidae of the World. 



13 



r No secondary tubercles or angular processes present on the 

 anterior margin of the head (or behind the clypeus when this 

 is exposed) between the outer tubercles and anterior angles , 

 the posterior plate of the prosternum almost always much 

 narrowed, often pointed, behind (American forms) 

 At least one pair of secondary tubercles or angular processes 

 present on the anterior margin of the head between the outer 

 tubercles and the anterior angles ; the posterior plate of the 

 prosternum more or less parallel sided, broadly truncate 

 behind (African forms) 



The clypeus exposed and separated from the irons by a distinct 



suture 

 The clypeus fused with the frons 2 and usually hidden 

 The outer tubercles obsolete or absent, the clypeus almost 



always exposed 3 

 The outer tubercles distinct, the clypeus rarely exposed 

 f The anterior margin of the head rarely with more than one pair 



of tubercles, 4 though these may be compound in structure ; 



the antennae rarely with less than four well developed 

 8x lamellae ; never with both these characters 



The anterior margin of the head always with two pairs of 



simple tubercles ; the antennae always with three well 



developed lamellae only „ .. 



4. 



Solenocyclinae, p. 68. 

 Pseudacathinae, p. 22. 



Procidinae, p. 32. 

 Passalinae, p. 43. 



Macrolininae, p. 76. 



Leplaulaeinae, p. 111. 



Subfamily AÜLACOCYCLINAE. 



Three of the genera defined in my previous account of this subfamily (1914c, pp. 192-3) 

 appear, in the light of further material, to be unnecessary. Two of these — Caulifer and 

 Auritulus — are monospecific, and may advantageously be merged in Aulacocyclus and 

 Cylindrocaulus, respectively. The third, Tristortlms , may also be merged in Aulacocyclus. 

 The best known species of Tristorthus is T. tricuspis, Kaup, from New Caledonia, a species 

 shown by its short antennal lamellae to be most nearly allied to the Australian species 

 of Aulacocyclus. With this are associated firstly, two other New Caledonian species, 

 apparently distinguished largely by differences in size, and in my opinion doubtfully 



1 The processes especially characteristic of the Solenocyclinae are situated immediately above the ventral tubercles. 

 Others may also, however, be present, and in all Malagasy forms a pair is more or less distinctly developed immediately 

 on the inner side of the fronto- vertical suture. The most primitive Malagasy genus, Malagasalus, lacks the former pair of 

 processes, and the above definition is applicable only by reason of its possession of the latter. The African and 

 Malagasy groups are composed, broadly speaking, of parallel series of genera separated largely by the presence or absence of 

 the latter pair of processes. I do not know of any African genus paralleling Malagasalm ; but if one exists the above 

 definition can hardly be expected to apply to it. See also above, pp. 10-11. 



2 Except in one species of Vindex (below, pp. 43 & 47) ; imperfectly fused in one species of Chnndrocephalus (below 

 pp. 43-45, fig. vi, 1). See also above p. 11. 



3 The clypeus is completely hidden only in the genus Platyverres, though in the transitional species Verres corticola 

 it is hardly apparent. In both these species the inner tubercles are situated on the anterior margin of the head and may 

 readily be mistaken for outer tubercles, though a comparison with other species of Verres, and especially with V. 

 cavicollis, at once settles their true homology. The heads of the species in question ara shown in fig v, p. 34. 



4 Only in the genus Tarquinius, which has six well developed antennal lamellae. 



