52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



from the tentorial pit toward the eye, as is Tanyrhinus (fig. ii A) 

 and Philonthus (fig. ii C). A definite postclypeal area is present in 

 Tanyrhinus (fig. ii A), Leptochirus (fig. loE), Osorius (fig. ii H), 

 Hypocyptus (fig. loD), Lorinota (fig. loL), etc. 



The posterior part of the epicranium is frequently marked by a 

 transverse suture which is believed to be the occipital suture. It is 

 generally rather short and disappears on the lateral aspect, but it 'may 

 extend onto the ventral surface, as in Oxyporus (fig. 12 D) and 

 Philonthus (fig. 12 J), In Aploderus (fig. 12 E) it even unites with 

 the gular sutures below. The following show this suture in some 

 form: Platystethus (fig. 10 G), Aploderus (fig. 12 E), Gastrolohimn, 

 Hesperobium (fig. 11 B) , Paederillus, Paederus, Lathrotropis, Stilicus, 

 Trachysectus, Orus, Astenus, Xantholinus, Staphylinus, Ocypus, 

 Philonthus (fig. ii C), Cafius, Glenus, Acylophorus (fig. u G), 

 Quedius, Oxyporus (fig. ii D), Bolitohius, Liparocephalus, Xenodusa 

 (fig. 10 K), Aleochara (fig. 10 F), and Baryodma. It should be noted 

 that Paederillus littorarius is the species having the suture, whereas 

 P. pugetensis apparently does not. Of the major subfamilies, only 

 Omaliinae and Steninae are not represented in this list. 



The head is frequently suddenly constricted behind at the point 

 to which it may be inserted into the prothorax. This point is fre- 

 quently but not always at about the region of the occipital suture. 

 Extreme examples of constriction are Metoponcus (fig. 11 E) and 

 Lorinota (fig. 10 L). 



The position of the antennal fossa varies considerably and has been 

 used extensively in classification schemes. Since the anterior arm of 

 the tentorium is invariably closely associated with the antennal fossa, 

 and the tentorial pits mark the posterior boundary of the frons or 

 frontal region, it follows that the antennae are never inserted " under 

 the margin of the front " or " at front of front " or " upon the front," 

 but can only be situated at some point along the anterior margin of the 

 vertex. In the cases in which the postclypeus is completely lacking, 

 the antennae will be inserted along the anterior margin of the head. 

 In those cases in which the postclypeus is present but does not reach 

 the eyes, the antennae will be inserted at the lateral corners of the 

 vertex, usually near the eyes. In those cases in which the postclypeus 

 is large and attains the eyes, the antennae will be inserted into the 

 upper surface of the epicranium, between the eyes. In the first group 

 are to be found all the Paederinae and Staphylininae, including Hes- 

 perohium (fig. 11 B), Metoponcus (fig. 11 E), Philonthus (fig. 11 C), 

 and Acylophorus (fig. 11 G). In the second group are all the Micro- 

 pepHnae, Omaliinae, Oxytelinae, Habrocerinae, and Tachyporinae, in- 



