North Ame?'ican Species of Trogophloeus. 327 



value of this element is also slight. The lateral elytral carina 

 is present in all; it is entire, and generally somewhat remote 

 from the edge. 



Many of the species resemble small, slender Aleocharini, and 

 ■especially the subgenus Hydrosmecta, but they can be distin- 

 guished at the first examination, not only by the position of the 

 antennae, but by the very coarsely faceted eyes, a striking char- 

 acter which they possess in common with Bledius andThinobius. 

 The number of species is probably enormous and in our own 

 <;ountry can scarcely fall far short of two hundred. 



The provisional grouping here presented has the faults of 

 nearly all subdivisions of large genera, in that there are several 

 intermediate forms; these, however, are very few in number, 

 and the exceptions should give rise to but little doubt. The 

 groups may be defined as follows: — 



Pronotum with a transverse arcuate groove near the base I, 



Species 1-4 

 Pronotum unimpressed or with two approximate, longitudinal impres- 

 sions in the middle of the disk and toward base, but without trace 

 of transverse impression. 

 Prothorax with the apical angles acute, anteriorly prominent and 



dentiform; sides subangulate II, 



Species 5-12 

 Prothorax without prominent anterior angles, the sides generally 

 more broadly rounded. 

 Eyes large, convex, and prominent, the tempora * short behind 

 them, much less prominent and usually acute at the posterior ex- 

 tremity, the head being limited behind by a well-marked trans- 

 verse constriction; sides of the prothorax sometimes very nar- 

 rowly rounded, approaching the subangular; disk of pronotum 



always bi-impressed III. 



Species 13-22 



Eyes small, much less prominent, the tempora behind them quite 



as prominent, more or less strongly arcuate, generally nearly as 



long as and sometimes longer than the eye; pronotum generally 



bi-impressed IV, 



Species 23-44 



^ The word tempora is used to designate the sides of the occiput, which 

 I have sometimes, less accurately, referred to as the post-ocular portions 

 of the genae in previous descriptions. This portion of the head playsna 

 important part in the internal classification of many Staphylinide 

 genera, and notably in the South American representatives of Sciocha- 

 ris. 



