68 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



Astenus (fig. 23 A) surpasses it somewhat though covered by the 

 coxae. Aleochara (fig. 22 A) has the shortest and most reduced 

 stenium. This structure is often produced posteriorly between or 

 under the coxae. Trigonnrus (fig. 22 Id) has a very small projection, 



Fig. 22. — Intrafamily variation in the form and structure of the 

 prosternal area (continued on fig. 23). 



A, Aleochara lata Grav. B, Lithocharis ochracca (Grav.). C, Osornis mundus 

 Shp. D, Triganurus crotchi Lee. E, Bledius monstratus Csy. F, Leptochirus 

 mexicanus Er. 



while the extreme development is reached in Astenus (fig. 23 A) and 

 Pinophilus (fig. 23 B). In these last two the prosternal lobe reaches 

 the lobes of the inflexed pronotum, thereby closing the coxal cavities 

 behind. In Pinophilus this closure is completed by the actual fusion 

 of the sternal lobe to the underside of the lateral lobes. 



