348 Coleopterological Notices. 



the various subgenera can be adequately appreciated only in a 

 general monograph. 



The metasternum 1 is usually longer in those species having well- 

 developed wings, but this difference is not always very pronounced. 

 The metasternal groove is as usual widely interrupted opposite the 

 abdominal process and becomes obliterated before attaining the 

 episterna. This groove has but little definite systematic value in 

 Emmenastus other than specific. In section I it is always very 

 strong and well developed, also in the single representative of 

 section III, while in section II it is well marked in some species 

 and more or less rudimentary in others, and, although in section IV 

 it is generally almost obsolete, its tendency to appear is frequently 

 indicated by a feebly impressed line of close irregularly placed 

 punctures. 



The sections as defined above are quite homogeneous with the 

 exception of II, which is still rather composite although in charac- 

 ters of minor value, the individual species being in every instance 

 widely isolated ; they are much more persistent in type in sections 

 I and IY. In section IV the hind Avings appear to be constantly 

 present but are always very rudimentary ; in obesus, for example, 

 they consist of an extremely small semi-membranous plate, scarcely 

 more than one-fourth as long as the prothorax, and in ater of a very 

 slender fillet of similar structure about as long as the prothorax. 

 In this section the apical margin of the head is not truncate but 

 broadly, more or less evenly arcuate and entire. In piceus and 

 pinguis there are two small distant feebly developed emarginations, 

 somewhat similar to those of Eurymetopon, but here they have no 

 systematic value whatever, and are not approached by or connected 

 in any way with the mandibles; the margin is almost invariably 

 entire, and these exceptions appear to be rather in the nature of 

 accidental and meaningless aberrations. 



The known species occurring within the limits of the United 

 States, including Lower California where they appear to be especi- 

 ally abundant, may be distinguished as follows : — 



1 In estimating the length of the metasternum and first ventral segment, the 

 distances are measured on a longitudinal line passing through the coxae, thus 

 representing the minimum length of each, and include the entire metasternum, 

 as the groove frequently hecomes obsolete in this genus. 



