KEYS TO FAMILIES OE CLAVICOKXIA. 



243 



aa. Elytra usually long, covering the greater part of the abdomen ; when 

 short the wings wanting or, it' present, not folded under the short 

 elytra when at rest; dorsal part of the abdominal segments partly 

 membranous. 



b. Tarsal joints on at least one pair of tarsi, five in number. 



Subseries B. Pentamera Clavicoknia, p. 243. 

 bb. Tarsal joints on all the tarsi less than five in number. 



c. Tarsi four-jointed (front ones three-jointed in the males of some 

 Mycetophagida?) . 



Subseries C. Tetramera Clavicoknia, p. 246. 

 cc. All the tarsi three-jointed. 



Subseries D. Trimera Clavicornia, p. 247. 



Subseries A. BRACII ELYTRA CLAVICORNIA. 



This group or subseries comprises but two families, whose mem- 

 bers subsist for the most part upon decaying animal or vegetable 

 matter, or occur beneath stones, in rotten wood or in the nests of 

 ants. 



KEY TO FAMILIES OF BRACHELYTRA CLAVICORNIA. 



(/. Abdomen not flexible; ventral segments 5 or 6; form short, robust; max- 

 illary palpi usually greatly developed and variable in form ; tarsi 

 with not more than three joints ; length less than 3.5 mm. 



Family X. Pselaphid^, p. 305. 

 aa. Abdomen flexible or capable of being curled upward ; seven or eight 

 segments visible from below ; form usually narrowed and elongated. 



Family XI. Staphylinid.e. p. 334. 



Subseries B. PEXTAMERA CLAYICORXIA. 



This group is composed, for the most part, of land and water 

 scavenger beetles whose office it is to hasten the decomposition and 

 removal of dead organic matter. They occur upon dead animals, 

 under the bark of dead trees and on decaying fungi, fruit, etc. Of 

 them Le Baron has written : ' ' The only other insects which can 

 be compared with these in usefulness as scavengers, is the extensive 

 family of Muscida?. in the two-winged flies. It is interesting to ob- 

 serve the order in which these various tribes of scavenger insects 

 perform their respective parts. First come the Aiuscidte, which, in 

 the form of carrion flies, deposit their eggs or fly-blows upon dead 

 animal matter at the first moment of decay, and. in very hot v T eather 

 almost immediately after life has ceased. Soon after these come 

 the carrion beetles, the Silphae and Neerophori, whose larvae, like 

 the maggots of the fiesh flies, are seen reveling in the putrescent 

 matter at the most offensive stage of decomposition. When the 

 softer parts have been devoured and only the osseous and liga- 



