AMERICAN COL.EOPTERA. 163 



terminal joint elongate-oval or subfusiform ; pointed, feebly com- 

 pressed ; penultimate joint of maxillary palpus short, subtriangular, 

 nearly as wide as long; of labial palpus more slender, feebly 

 widened externally. Antenna? 9 , 10-, or 11 jointed, the stem not 

 at all serrate, the three or four joints preceding the club very 

 short; last three joints much wider and together longer than all the 

 preceding, longer and relatively narrower in the male. Prothorax 

 with entire side margin, which is finely somewhat irregularly ser- 

 rate; front angles distinct, nearly right; hind angles broadly 

 rounded and ill defined ; disk more or less elevated posteriorly, the 

 elevation usually somewhat compressed laterally. Surface of head 

 and thorax finely granulate; elytra punctate-striate, the lines of 

 punctures sometimes a little irregular. Prosternum scarcely as long 

 before the coxa? as the coxal diameter, the coxa? usually contiguous 

 or nearly so, the intercoxal process acute, becoming laminate poste- 

 riorly except in sericans and tenellus, in which it is wider and the 

 coxa? not contiguous. Middle coxa? narrowly but evidently separa- 

 ted. First, third and fourth ventral segments nearly equal and 

 shorter than the second and fifth. Basal joint of tarsi subequal to 

 the three following; third and fourth joints emarginate above for 

 the insertion of the joint following, except in tenellus, in which the 

 fourth only is very feebly emarginate. 



The relation of Oligomer a* to allied genera is sufficiently well 

 indicated in the table of genera. The number of antennal joints 

 does not here constitute a generic character, unless the instability 

 itself be so considered ; in fact the number seems to vary individu- 

 ally in one species (obtusus). In a series of twenty-three specimens 

 not otherwise separable, ten have the antennas 11-jointed, twelve 

 have them 10-jointed, and in the remaining example one antenna is 

 10 and the other 11 jointed. In the 10-jointed antenna the fourth 

 joint is about equal in length to the third, and usually shows a more 

 or less evident constriction or impression, and in some examples this 

 pseudo division is so distinct that it is very difficult to say whether 

 the organ contains ten or eleven joints. When the division is com- 

 plete the fourth joint is left evidently shorter than the third. In 

 those species with 9 jointed antennae I have observed no tendency to 

 variation, though it may possibly occur, nor does there appear to he 

 any in sericans. Of the two European species brunneus has 10- 

 jointed and reyi 11-jointed antenna?. I do not know whether any 



TRANS. AM. ENT. SOC. XXXI. MAY. 1905. 



