42 ILLISOIS BIOLOGICAL MOSOGR.iPHS (42 



nor laminatentorium and rudimentary supratentorinae; that of Molamba 

 the most rudimentary tentorium of any genus included within this study. 

 No clearer illustration of the difficulties of indicating relationship can be 

 shown than that exhibited by the families of the Silphoidea. 



A study of the Staphylinoidea (Figs. 22, 25-35,170-181,317-328,463- 

 473) shows that the various genera of the Staphylinidae have considerable 

 homogeneity. Tachinus departs the most from the characteristic condi- 

 tion, in possessing a much more generalized dorsal surface than the other 

 members of this family. The Staphylinidae possess a tentorium and a 

 ventral surface similar on the whole to that of the Adephaga and the 

 Hydrophiloidea. Tachinus, through the added similarity of its dorsal 

 surface, would seem to bear a particularly close relationship to these 

 groups. The Sphaeriidae, as represented by Sphaerius, and the Ptilidae, as 

 represented by Limulodes, possess a primitive condition of the metaten- 

 torinae, while Scaphidium and Hister possess confluent gular sutures. 

 The Pselaphidae, as represented by Pilopius, and the Clavigeridae, as 

 represented by Fustiger, in form of head and character of the ventral surface 

 and tentorium show a close relationship to Connophron. The irregu- 

 larities of structure displayed by the families of this group are nearly as 

 great as those displayed by the families of the Silphoidea. Both of these 

 superfamilies probably need considerable revising. 



All of the genera of the Cantharoidea (Figs. 36-42, 182-190, 329-335, 

 474-480) possess complete epicranial arms and dorsal portion of the anten- 

 nariae, and lack of corpotentorium, except the Cleridae and the Coryne- 

 tidae, represented by Trichodes and Necrobia respectively. All possess a 

 complete gula e.xcept the latter genera and CoUops, the representative of 

 the Welyridae. This superfamily can be divided into three subgroups. 

 One group will include the Lycidae and Lampyridae, characterized by a 

 globular head, short broad gula, and absence of the pretentorinae. A 

 second group will include the Phengodidae and the Cantharidae, char- 

 acterized by a longer and flatter head and longer gula. The third group 

 will include the Cleridae and the Corynetidae, possessing short incomplete 

 arms, incomplete gular sutures, and a well developed corpotentorium. 

 CoUops does not seem to fit in very well anywhere, though this genus, 

 through the form of its dorsal surface and tentorium may possibly lean 

 towards the second group. Cantharis, of the second group, is peculiar in 

 possessing a normal gula, whereas in the other forms the gula is rudimen- 

 tary, though in all other respects this genus is like the other members of 

 this group. The first and second groups are no doubt closely related. The 

 latter is probably the more generalized, possessing a dorsal surface resem- 

 bling to a marked extent the dorsal surface of the Carabidae. The gula, 

 in so far as it is complete, also resembles the condition of this structure in 

 the families of the Adephaga, and particularly in Necrophorus, of the 



