OF THE DOR-BEETLE. 91 



beetle is digging, the antennje lie down on the under-side of the 

 head (Fig. 2, a), thus forming an additional protection to the eyes, 

 whilst the clubs of the antennae are securely lodged in cavities on 

 the under-side of the pro-thorax, or, more properly speaking, the 

 pro-sternum. 



The mouth-organs, as may be expected, are not very powerful, 

 seeing that the beetle feeds on material which has already gone 

 through a very perfect process of trituration. The mandibles do 

 not exhibit that peculiarity of form which may be seen in the 

 species of Geodephaga and others, the right and left mandible 

 being precisely alike. The various species of this genus have 

 their mandibles formed rather differently externally. For instance, 

 G. stercorarius (Lin.) has a hollow near the top, and then the out- 

 line continued in one uniform curve, whereas, in the one under 

 our notice, there are two hollows followed by a tolerably straight 

 portion. The tips of the mandibles are of a chisel form, and act 

 in the same way as the incisor teeth of the Rodents. The whole 

 of the inside edge on the under side is set with hairs and bristles, 

 and from about half way down to the root the mandible is of 

 a peculiar structure (Figs. 4 — 5) ; it appears to be membranous, 

 with about thirty longitudinal ridges, each of which is again ridged 

 or striated transversely. The use of this is, no doubt, to assist in 

 sweeping the food into the centre part of the mouth, and prevent 

 its escaping, which must be very necessary, as the beetle feeds on 

 such a soft semi-fluid pabulum. The labrum (Fig. 3) is of a some- 

 what rectangular form with the corners rounded, but the most 

 remarkable part about it, is the way the under side is set with 

 hair and stiff bristles recurved inwards, evidently also to assist in 

 retaining the food in the mouth. Referring to the under side of 

 the head, the mentum is very elongate, and deeply emarginate in 

 front. The labium is very short and fleshy, and its palpi with the 

 usual number of four joints is moderately short. The maxillae are 

 only peculiar inasmuch as the lacinige, or blades, are not very 

 large, and are clothed with hair, and have not the well-developed 

 hooks to their tips, which is so strikingly shown in the Geodep/iaga, 

 their palpi are very short, and the inner lobes are in the form of 

 a wide, flat brush. 



The thorax consists of three portions : the prothorax, meso- 



