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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



at the middle. The condyles are fairly constant in position. The ven- 

 tral one is a rounded protuberance and is located on the proximal 

 end of the ventral side near the outer angle. In Oxyporus (fig. 16 H) 

 this condyle is situated much nearer the inner edge. The dorsal ar- 

 ticulation is sometimes a definite rounded acetabulum but frequently 

 is only a hollow curve along the face of an irregular projection. The 

 prostheca ofifers considerable variety in form, size, and position. It is 



Fig. 16. — Intrafamily variation of the mandibles (continued from fig. 15), 



A, Pclccomnlium tcstaceum (Mann.). B, Hypocyptus longicornis (Payk.). 

 C, Pacdcrillus pugctcnsis Csy. D, Stcnus scuJptUis Csy. E, Lithocharis ochracea 

 (Grav.). F,.AcyIophonts flavicoUis Sachse. G, Hesperohimn pallipcs (Grav.). 

 H, Oxyporus lateralis Grav. I, BIcdiiis nwiistrafiis Csy. 



apparently lacking in Micropcplus (fig. 15 C), Astcnus (fig. 15 L), 

 and Stenus (fig. i6 D) . In Glenus (fig. 15 K) , Paederilhis (fig. 16 C) , 

 and Creophilus (fig. 2 F) the prostheca is a definite projecting lobe 

 with numerous minute hairlike processes, while in many other species 

 it is apparently represented by a more or less definite row or area 

 of processes proceeding from the surface of the mandible or a groove 

 thereon, such as in Pelecomalium (fig. 16 A), Proteinus (fig. 15 A), 

 Acylophorus (fig. 16 F), Oxyporus (fig. 16 H), Bolitohhis (fig. 

 15 H), and Xcnodusa (fig. 15 D). 



