296 STAPHYLINIDA. 
emargination of the front of the thorax, into which is exactly fitted another piece of a 
transverse form, and this small piece (all that can be seen of the head from above) is 
the posterior part of the upper surface of the head. When the insect is viewed from 
beneath it is seen that the rest of the upper surface of the head is abruptly infolded, 
so that it forms part of the lower aspect of the body, the parts of the mouth being 
accordingly placed quite beneath the insect and even at some little distance from the front 
margin; the head, however, is quite as accurately adapted to the thorax on this aspect 
of the body as it is on the upper surface, so that, indeed, it appears actually to be a 
portion of the large thorax. The head, however, is capable of a slight extension from the 
thorax, and when this is accomplished there is exposed a large emargination on each 
side, so that two lateral projections are formed, and above these and concealed between 
them and the thorax are placed the short stout antenne, of an uncertain number of 
joints. The mouth is entirely closed by the rather large labrum, which meets the front 
of the mentum, this latter being concealed, when the head is retracted, by the front of 
the prosternum : a large portion of the body of the maxilla is exposed, attached to which, 
and conspicuously exserted, is the slender and rather long maxillary palpus; the first 
visible joint of this palpus is small and oval; the second is slender, twice or three times 
as long as the first; the terminal joint small and slender, almost setiform. No trace of 
eyes can be detected either on the upper or under surface of the head. The portion of 
the prosternum displayed in front of the anterior coxe is rather large, and the coxe 
themselves are nearly globular and are rather widely separated by the extension 
backwards of the prosternum; this prolongation becomes broader behind the cox, and 
is prolonged far backwards, so as to project as far back as the hind margin of the 
pronotum; it is deeply emarginate behind, and reposes on the metasternum ; the sides 
of the prosternum are completely folded in and closely applied to the upper face of the 
thorax. The mesosternum is large and is folded in the middle, so as to form a 
projection reposing on the upper face of the prosternal process, and joining behind a 
projection of the metasternum, which extends forwards under and between the rather 
widely separated middle cox. The hind coxe are broadly separated, and form each a 
large lamina, rather larger than the metasternum, and extending outwards, becoming 
rather longer externally, to the epipleura ; the other parts of the hind leg are concealed 
behind this lamina. Six ventral segments, all very mobile, are visible besides the 
genital armature. The.sides of the wing-cases form a free edge, as in the more highly 
evoluted of the species of Erchomus. On the dorsal aspect there are visible four 
segments of the hind-body in addition to that of the armature, and at the base behind 
the margin of the wing-case the side piece of the preceding segment is displayed. There 
appears at first to be no margination of the sides of this part; but more careful 
inspection reveals that the margins are really extremely large, but that they are 
completely adpressed on the dorsal surface, so as to form actually a large addition to the 
superficies of the upper surface of the hind body. 
