56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



tentorial pits, however, are located in this species near the base of the 

 labium and indicate a possible relationship with the supposedly closely 

 related XanthoUnus, in which the sutures are confluent on the midline. 



THE APPENDAGES OF THE HEAD 



The intrafamily variation in the antennae is considerable, but these 

 variations are mostly rather superficial and are not very constant 

 within the subfamilies. Omitting the aberrant Micropepliis (fig. 

 13 M), in which the antenna is only nine-segmented with a much 

 enlarged terminal segment, the forms are either lO- or ii-segmented. 

 In the former group are the Hypocyptini (fig. 13 N) and two genera 

 of the Aleocharinae {Oligota and Dcciisa). All other members of the 

 family examined have the antennae clearly 11 -segmented. 



Figure 13 shows some of the variations in form of the antennae. 

 The method of insertion of the second segment into the first deter- 

 mines the amount of movement possible as well as the amount of 

 geniculation. Strongly geniculate antennae are found in Acylophorus 

 (fig. 13 L), Osorius (fig. 13 K), and some of the Paederini (subtribe 

 Cryptobia). Great variation is found in the shape of the basal seg- 

 ment, as well as in its size and method of insertion in the antennal 

 fossa. 



The vestiture of the antennal segments ranges from the large sparse 

 tactile setae of figure 13 I to the dense minute pile indicated on the 

 distal segments of figure 13 H. No segment anywhere has been ob- 

 served that is entirely without vestiture, though on some (as fig. 13 L) 

 it may be exceedingly minute and indistinct. The exceedingly minute 

 vestiture is generally accompanied by numerous pores, which give a 

 glandular appearance to the surface (fig. i B). The extent of this 

 type of vestiture is rather definite in each species and varies con- 

 siderably throughout the family. In some it is distinctly confined to 

 certain segments, but in others diminishes gradually from the apex 

 and becomes indistinct on the basal segments. In Micropeplus only 

 the terminal (ninth) segment is so clothed. Creophilus has this type 

 of vestiture on the last five segments ; Hadrotes on the last six. Those 

 with it on the last seven include Tanyrhinus, Leptochirus, Glenus, 

 Bolitohius, and Aleochara. Those with it on the terminal eight seg- 

 ments include Oxytelus, XanthoUnus, Philonthus, and Quedius. The 

 following have it on all but the two basal : Gastrolohiuin, Lathrotropis, 

 Hesperobium, and Pinophilus. From this it can be seen that the vesti- 

 ture of the antennae is not stable within certain tribal limits, and in 

 some cases even in smaller groups there is considerable variation. 



