44 



Memoirs of the Indian Museum. 



[Vol. VII, 



The fourth genus, Paxillus, is distinguished from all others by having more than three 

 well developed lamellae on each antenna. In some species the clypeus is exposed and 

 in others it is hidden ; but all are closely related to one another and as they are not very 

 numerous all the genera which have been established for them may conveniently be united 

 into one. It is probable that a considerable proportion of the species that have been 

 described are invalid (see Arrow, 1907, p. 443). 



The remaining species, though undoubtedly numerous, probably require proportionally 

 still more drastic reduction of their numbers. It seems to be impossible to separate 

 them into groups having the same value as the genera mentioned above. Consequently 

 I propose to regard almost all of them as constituting a single large and plastic genus 

 Passalus. 



The only exception is the genus Ptichopus, the last and in some respects the most 

 highly specialized genus of the subfamily. It may readily be recognized from all others 

 by the remarkable structure of its mandibles. 



The genera of Passalinae known to me may be separated thus : — 



f The clypeus clearly exposed ; the antennae with not more 

 j than three well developed lamellae 



J The clypeus hidden 1 ; or, the antennae with more than three 

 (^ well developed lamellae . . 



!The dentition normal ; the clypeus more or less horizontal Chondrocephalus, p. 44. 

 The dentition reduced ; the clypeus more or less vertical . . 

 ( Much flattened insects with the inner and outer tubercles 

 ] almost in a straight line on the upper part of the anterior 

 j margin of the head, and projecting forwards above the clypeus Vindex, p. 46. 

 (^ Robust insects with the cephalic tubercles normally situated Proculejoides, p. 47. 

 ( The antennae with more than three well developed lamellae ; 

 the clypeus exposed or hidden 

 The antennae with not more than three well developed 



lamellae ; the clypeus hidden 1 

 The dentition normal 



The upper terminal tooth very large and acute, directed 

 forwards ; the middle one rudimentary or absent ; the 

 lowest one very small, directed inwards 



2. 



4. 



3. 



4< 



Paxillus, p. 48. 



Passalus, p. 51. 



PticJwpus, p. 68. 



Genus CHONDROCEPHALUS, Kuweit, 1896, p. 221. 

 Type, Popilius granulifrons, Bates, 1886, p. 12, pi. i, figs. 13- 13a. 



Chondrocephalus quinquecornutus, n. sp. 



Fig. VI, 1. 



Two complete specimens from Guatemala and one dissected head. Length 17 mm. 



The lamellae of the antennae are moderately long and slender. The anterior lower 



tooth of the left mandible is broad and more or less distinctly bidentate, that of the right 



1 Exposed to some extent in Passalus guafemalensis ; see below, p. 57. 



