THE IHSTER BEETLES. 599 



of the abdomen uncovered. In form they are variable, either ob- 

 long and flat or, more usually, round, oval, globose or cylindrical. 

 All are very compact, have a very hard surface and the elytra are 

 usually marked with a number of stria 3 . According to species, these 

 vary much in number, length and connection and are therefore 

 much used in classification. The beetles live for the most part under 

 the bark of logs, in decaying fungi, carrion, animal excrement or 

 ants' nests. They were formerly thought to be scavengers, but it 

 is now believed they are predaceous in all stages, and devour the 

 larva? of Diptera and other forms which are feeding upon the de- 

 caying matter. 



The name Hister is usually supposed to have been derived from 

 the Latin liistrio, meaning a clown or mimic, and to have been ap- 

 plied to these insects by Linnams on account of their habit of re- 

 tracting the antennae and legs and feigning death when disturbed. 

 However, LeConte states * that as a vast number of other insects 

 feign death in the same manner, this derivation appears inappro- 

 priate. He therefore suggests that as the Roman poet Juvenal, in 

 one of his satires, mentions a filthy fellow of the name of Hister. 

 Linnasus, who was fond of alluding to the classic writers of Rome, 

 on finding these beetles living in the most filthy condi- 

 tions, in the midst of excrements and putrefaction, 

 probably, and very properly, gave this name to them. 



In addition to the characters mentioned, the mem- 

 bers of the family have the antennae elbowed or ab- 

 ruptly bent and retractile (Fig. 229), the first joint Fig. 229. 

 long, the eighth and following joints forming a com- 

 pact, rounded or rarely triangular club; thorax closely applied to 

 the elytra, usually with cavities beneath the side margins to receive 

 the clubs of the antenna?; prosternum frequently lobed in front and 

 prolonged between the front coxae, the latter transverse or globose, 

 the cavities open behind ; middle and hind coxaa rounded or subquad- 

 rate, widely expanded ; abdomen with five free ventral segments, the 

 first very large, the fifth very short; legs short, retractile; tibia 1 com- 

 pressed, front ones toothed and more or less fitted for digging; tarsi 

 slender, short, 5-jointed (except in Acritits and Jllctes, w T here the 

 hind ones are 4-jointed), the front ones usually received in grooves 

 on the front face of the tibiae. 



The principal literature treating of the North American mem- 

 bers of the family is as follows: 



*Proc. Phil. Acad. Nat. Sci., XI, 1859, 310. 



