Casey — Observations on the Staphylinidae. 127 



the mode of antennal insertion differs in the two subfamilies. 



Assuming, therefore, a subfamily Aleocharinae constituted 

 as above, it may be subdivided into a number of tribes de- 

 pending upon tarsal, antennal and other characters, to which 

 simple group names have been hitherto attached. For ex- 

 ample, the Aleocharini comprise those genera of the former 

 heterogeneous tribe Aleocharini having the antennae 11-jointed 

 and the tarsi 5-5-5-jointed, the Myrmedoniini those with 

 similar antennae but having the tarsi 4-5-5 jointed, then the 

 Bolitocharini with the tarsi 4-4-5 jointed and so on through 

 the series. These tribes may then be further subdivided into 

 subtribes based upon various less important structural pe- 

 culiarities. The Aleocharini would include, for instance, a 

 subtribe Aleocharae, including all those genera of the tribe 

 Aleocharini having a small additional or fifth joint at the tip 

 of the slender fourth joint of the maxillary palpi and the 

 Oxypodae would be a subtribe characterized by a narrower and 

 less heavy body, as a rule, and absence of the palpal appen- 

 dage ; there would also be other subtribal groups defined by 

 special characters. 



In the following pages I have selected for systematic study 

 certain of these subtribal groups of genera as they occur in 

 America. 



Tribe Aleocharini. 



Subtribe Aleocharae. 



This subtribe of the restricted tribe Aleocharini is well 

 represented in America by numerous genera which may be 

 defined as follows, the table including also all the known 

 European genera : — 



Hypomera strongly inflexed, not at all visible from a lateral point of view. 2 



Hypomera feebly inflexed, in part at least visible from a lateral point of 



view in a horizontal plane passing through the axis of the body II 



2 — Mesosternum without trace of carina at any point; elytra not sinuate at 



tip externally 3 



Mesosternum carinate, the carina generally extending to the tip of the 

 process but sometimes abbreviated • 5 



3 — Abdomen with the first three tergl^s narrowly and acutely impressed 



