ANT AND TERMITE GUESTS 



193 



We know so far 333 living species, divided over sixteen 

 genera. In addition there are five extinct species, of 

 which four lived in the lower Oligocene and therefore 

 in the first third of the Tertiary period. Three of 

 them belong to the still living genera Arthropterus and 

 Paussus ; one, Paussoides, is only known as a fossil. 

 There is also a Paussus of the Diluvial period (pre- 

 served in Copal). The Paussidae show the nearest 

 systematic relationship with the Carabidae and with 

 the group of Bombardier beetles (Brachyninae) to 

 which the most primitive Paussidae genera closely 

 approach. Since the Carabidae appeared already in 

 the Trias and in the Lias and since the Brachyninae 

 are already represented in the upper Chalk and the 

 lower Oligocene, hence they, palaeontologically, are 

 to be assumed as the ancestors of the Paussidse. 



As with the Staphylinidae, Clavigeridae, and Paussidse 

 so it is with the Gnostidae, Ectrephidae, Pselaphidae, 

 Scydmaenidae, Thorictidae, Rhysopaussidae, Endomy- 

 chidae, Silphidae, Lathridiidae, Histeridae, Scarabaeidse 

 Brenthidae, etc., which partly represent some myrme- 

 cophil or termitophil families or sub-families and partly 

 embrace a larger or smaller number of myrmecophil 

 or termitophil genera and species, whose systematic 

 characters attribute themselves as adaptive characters 

 to the myrmecophil or termitophil mode of existence. 



Furthermore we find also in the insect order of the 

 Diptera or two-winged flies a series of similar examples. 

 The Termitoxeniidae form a special family (or sub- 

 family) which embraces exclusively Termite guests, 



