19 



does not appear to have actually examined any Systellopid spe- 

 cies, and that it is Dr. Sharp who states that it is the labrum 

 which in the Systellopides is attached to the front of the clypeus 

 and is on the same level with it. I do not venture to assert that 

 either of these accomplished entomologists (both extremely 

 eminent anatomists) is wrong, — which would be highly presump- 

 tuous in any but a specialist on anatomy, — but I draw attention 

 to the matter in order to show that Lacordaire's method of dis- 

 tinguishing the Sericides from the Sericoides is at any rate not 

 easy of application to the ordinary student. 



However, there can be no doubt that these sub-tribes of 

 Melolonthini form two very natural and distinct aggregates in 

 each of which moreover there is a highly characteristic relation 

 between the clypeus and labrum, and I think this can be 

 expressed in terms (different from those of Lacordaire) which at 

 any rate as a supplementary statement of characters will be 

 found useful inasmuch as it avoids the necessity of determining 

 in difficult cases whether the front piece of the head is or is not 

 a true labrum. 



In the Sericides, whether we regard the front piece of the head 

 as a labrum or follow Lacordaire in regarding it as an extension 

 of the clypeus and the labrum as invisible, it stands good that the 

 front face of the front piece of the head looked at from in front 

 has very little downward vertical or oblique development, so that 

 the insertion of the palpi is very little below the plane of the 

 clypeus, but in the Sericoides it is far otherwise. In them 

 (and also in the true Melolonthides), the labrum is attached to 

 the clypeus at a position considerably below the plane of the 

 upper surface of the latter, so that if the latter be looked at 

 from in front it seems to be strongly thickened downward (in 

 some species obliquely downward and hindward) and the labrum 

 is attached to it at a point considerably down this thickened 

 front face. As in the Sericides so in Sericoides there are genera 

 in which the labrum is not very easy to see as an organ distinct 

 from the clypeus, and moreover the labrum itself is of very 

 variable form in the Sericoides (in some genera even becoming 

 an erect lamina the apex of which rises considerably above the 

 plane of the clypeus) ; nevertheless a result of the attachment of 

 the base of the labrum being as indicated above is that the palpi 

 are inserted considerably below the plane of the upper surface of 

 the clypeus and all the observations I have made confirm the 

 opinion that their being so inserted is reliable evidence that the 

 relation of the clypeus and the labrum are of the Sericoid rather 

 than the Sericid type. 



The adoption of this s^iew of the distinctive characters of the 

 Australian Sericides and Sericoides involves some little re-adjust- 



