454 Mr. Westwood on some new Species o/'Athyreiis, 



The maxillae (Tab. XXII. fig. b) also exhibit an interesting structure in 

 Athyreus orientaUs which I have not seen in other Lamellicorn insects : the 

 upper lobe terminates in a broad piece, having a sharp point at its angle 

 within the mouth ; whilst the lower lobe has two horny processes ; the upper 

 one is broadly-truncate and flat, occasionally, as appears from the figures of 

 Klug and Curtis, bidentate, but in the species which I examined scarcely 

 emarginate ; the lower lobe is also flat, but its side is furnished with a series 

 of about seven very short thick bristles pressed together, which must evi- 

 dently be of peculiar use in the act of mastication. The structure of the 

 lower parts of the mouth has been entirely misdescribed by Mr. MacLeay ; 

 the mentum (Tab. XXII. fig. c), instead of being deeply emarginate, has the 

 middle of its fore margin advanced further than the lateral angles; the 

 scapes, to which the three-jointed labial palpi are attached, are slightly pro- 

 minent and furnished with short bristles, and the whole of the underside of 

 this organ is densely clothed like the rest of the body with very long bristles. 



Other peculiarities of the present genus consist in the very great width of 

 that part of the metasternum which occurs between the two middle feet 

 (Tab. XXII. fig. d)*, which are thereby inserted much more widely apart 

 than the hind-feet ; the very short abdomen, which causes the hind-feet to 

 appear as if placed almost at the extremity of the body ; and the great length 

 of the hind tibiae and tarsi. The figure given by M. Gu^rin M^neville of 

 the underside of the body of Athyreus castaneus, in the ' Iconographie du 

 R^gne Animal,' in order to exhibit these peculiarities, is far from correct, the 

 metasternum being marked both with transverse and longitudinal lateral 

 incisions which do not exist in nature, and which consequently lead to a very 

 incorrect idea of the real structure of the underside of the body. 



On comparing these peculiarities of organization with those of Geotrupes, 

 the typical genus of the family to which Athyreus has been referred, we are 

 bound to admit the correctness of Mr. MacLeay's observation, that this 

 genus is one of its extreme forms. We here find indeed, in common with 

 Geotrupes, a porrected upper lip and laterally exposed horny mandibles, but 

 the structure of the maxillae and mentum is very different ; and entomologists 

 need not be reminded that it is to these latter organs especially that they 

 look for the indication of the nature of the food and the consequent variations 



* This and the other figures of generic details are derived from Athyreus orientaUs. 



