374 



as two planes meeting each other, one of which (I call it the 

 lower plane) is inclined from the line of junction with the 

 other (which I call the upper plane) hindward and downward 

 (the insect being laid on its back) towards meeting tJie 

 labium ; the upper plane is inclined from the line of junction 

 upward or horizontally towards the front edge of the clypeus. 

 But outside this common feature of the labrum there is the 

 greatest possible diversity. In some species the upper and 

 lower planes meet at an angle, the line of junction in some 

 species even being defined by a fine transverse carina; while 

 in others the two planes meet in a rounded manner. In 

 some species the upper plane is horizontal, in others perpen- 

 dicular, or inclined in diverse ways to the horizontal. In 

 some species the labrum is entirely below the level of the 

 clypeus, in others it overtops the clypeus. In some species 

 having the labrum entirely below the clypeus, but more or 

 less perpendicular, it appears when viewed from the front 

 as an arch of uniform height, in others as an arch much more 

 strongly curved on the upper than the lower edge, in others 

 as a triangle, and in others again as an elongate erect 

 lamina. 



The puncturation of the various segments of the body 

 is, of course, a character of great importance in distinguish- 

 ing the species of this genus — but it is obviously diffi.cult 

 to express in terms that lend themselves to a tabular state- 

 ment where the difference in puncturation is not very gTeat. 

 In the following pages I have in some cases endeavoured to 

 meet that difficulty by counting the number of punctures 

 occupying a given space, and I have also made use of a differ- 

 ence that is easily traceable in the type of puncturation on 

 the elytra. In many species the punctures are isolated round 

 holes, normally impressed on the surface, while in others they 

 appear as impressions of more or less triangular form, more 

 deeply sunk at the base than at the apex, with the result 

 that if the elytra be viewed obliquely from behind the front 

 limit of the punctures seems to be raised in a granuliform 

 manner. The term ''squamose" has been commonly applied 

 to that latter style of sculpture from its causing a more or 

 less scale-like appearance from some points of view, and I 

 have made use of the term in the following pages. It is 

 desirable, however, to remark that I limit the term to those 

 elytra in which the prevailing character of the sculpture is 

 squamose; there are some species in which the general punc- 

 turation is distinctly of the non-squamose type, but on 

 which, nevertheless, when they are viewed obliquely from 

 behind a few granules can be seen — usually about the base 

 and suture. It is perhaps well to note here that where a 



