54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



eluding Micro pe plus (fig. lO B) , Pelecoiiialiuin (fig. lo J), Tanyrhinus 

 (fig. II A), Proteinus (fig. 10 I), Lcptochirus (fig. 10 E), Platy- 

 steihus (fig. 10 G), Osorius (fig. 11 H), Oxyporus (fig. 11 D), Hy- 

 pocyptus (fig. 10 D), Tachyporus (fig. loC), and Bolitobiiis (fig. 

 II F). In the third group are all the Steninae and Aleocharinae, in- 

 cluding Stenus (fig. 10 H), Xenodusa (fig. loK), Lorinota (fig. 

 10 L) , and Alcochara (fig. 10 F) . It should be noted that Acylophorus 

 shows a tendency toward the second group, whereas Hypocyptus seems 

 to approach the third group. 



The compound eyes are normally situated at the sides of the head 

 but frequently slightly more on the dorsal aspect than on the ventral. 

 They vary greatly in size, as in Stenus (fig. 10 H) and Leptochirus 

 (fig. 10 E) . They are so far as observed always complete and undivided 

 and never more than slightly emarginate at any point. The facets 

 vary considerably in relative size and in convexity, and may be inter- 

 spersed with fine hairs, as in Liparoccphalus. 



The opening from the eye into the interior of the head is the 

 ocular foramen. It is generally much smaller than the eye itself be- 

 cause of the development of the oculata. The ocular foramina are 

 indicated in figure 12 F by two small dotted circles near the eyes. 

 Ocelli are present in one subfamily — the Omaliinae. They appear to 

 be entirely characteristic of this group, being found only here and 

 in all the members except one genus which is doubtfully retained. 

 This genus, Vellica, has not been available for study. The ocelli are 

 situated on the vertex, one on each side, between or behind the 

 posterior parts of the compound eyes. In dried specimens they usually 

 appear as pale convex protuberances, but in slide preparations are 

 visible only as lighter spots in the wall of the vertex where the sclero- 

 tization is less thick or the pigment less evident. The ocelli are indi- 

 cated in the drawings by solid lines and must not be confused with 

 the ends of the dorsal arms of the tentorium, indicated by dotted lines. 

 Tanyrhinus (fig. 11 A) and Pclecomaliwn (fig. 10 J) illustrate these 

 organs. 



The anterior tentorial pits as already stated mark the position of the 

 epicranial arms or frontal sutures. Since the frons is apparently al- 

 ways missing in this family, a line between the anterior tentorial 

 pits may be taken as the line of fusion of the postclypeus and vertex. 

 The tentorial pits are always situated near the antennal fossae, usually 

 at their mesal or anterior corners. They may be situated at some point 

 on the surface of the epicranium before or between the eyes. They 

 are shown in the figures as black spots but are seldom, if ever, visible 

 from the exterior in dry specimens. Their actual location is to be 



