Casey — Observations on the Staphylinidae. 183 



Tribe Myrmedoniini. 



The genera of this tribe here defined have a certain com- 

 munity of facies which is rather difficult to characterize rig- 

 orously, but resulting mainly from the fact that the head and 

 prothorax are always narrower than the elytra, with the 

 former strongly constricted at base and the sculpture of the 

 abdomen more or less sparse, the first two or three tergites 

 being deeply and conspicuously impressed at base. They are 

 the genera that range themselves about Gnypeta, Tachyusa 

 and Falagria. Possibly some European genera placed in 

 proximity to these three genera in the catalogue of Heyden, 

 Keitter andWeise, other than those defined in the accompany- 

 ing tables, should be included, but it is certain that Echid- 

 noglossa, placed next to Falagria in that work, should be 

 excluded, as the tarsi are all 5- jointed and Thinonoma 

 Thom., and Brachyusa Rey, which come after Gnypeta, are 

 also to be excluded, they having scarcely any points of habital 

 resemblance. Ischnopoda and Xenusa, however, seem to be 

 close allies of Gnypeta and are included in the following 

 table. These genera form two independent subtribes of the 

 Myrmedoniini as follows: — 



Prosternum wholly membraneous under the coxae ; neck only moderately 

 narrow Tachynsae 



Prosternum corneous under the coxae, either wholly or partially; neck very 

 slender Falagria© 



These subtribes both include numerous genera. 



Subtribe Tacbyusae. 



In delimiting the genera of this subtribe considerable tax- 

 onomic value is attached to the form of the intermediate 

 acetabula, whether sharply outlined throughout by a fine 

 beaded edge — closed, — or having the beaded edge widely 

 interrupted behind, the bottom of the cavity merging grad- 

 ually through a continuous convex surface into the meta- 

 sternum — open. Other characters which are held to be of 



