54 THE ORDER OF COLEOPTERA. 



A. Mirlflle and hind tarsi with the first four joints short; the last often as long as all the others; 



Ijoily oliloiifj ; thorax furrowed, and narrower than the elytra ; size small Helophokiis. 



A A. Middle and hind tarsi with second joint elongated, first very short ; body oval ; thorax as 

 wide at base as elytra. 

 B. Metasterniim keeled and prolonged backward into a sharp spine ; tarsi flattened; size largo 



or very large Hydkoi'HIlus . 



B B. Metasternum not prolonged ; tarsi not compressed ; size small or very small. 



C. Hind tibiif and tarsi ciliate ; sciitellitm elongated Bkkosis. 



U C. Hind tibi;e and tarsi not ciliate ; sciitellum regularly triangular Hyiirokius. 



AAA. Atiddle and hind tarsi with the first joint elongated ; bodj- short and sub globular ; size very 

 small ; not aquatic ; found in cow-dung .SriicEuiiuUM. 



TUDiK IV. 



LAND SCAVENGER BEETLES. 



Putrirom ferrestria, Necrophaga partli/, Ivatreille. 



This tribe embraces au extensive series of useful scavenj^ers, whose 

 office it is to hasteu the clecompositiou aud removal of dead orgauic 

 matter. The typical species are found upon dead animals or other de- 

 composiiijif animal substances. Sotoe of the smaller species are found 

 under the bark of dead trees 5 Avhilst others feed upon fungi, especially 

 those which grow ui)on decaying trees. The only other insects which 

 can be conii)ared with these in usefulness as scavengers, is the extensive 

 family of Muscidce, in the two- winged Hies. It is interesting to observe 

 the order in which these various tribes of scavenger insects perform their 

 respective parts. First come the INIuscidiv, which, in the form of carrion 

 flies, deposit their eggs or Jiy-hlows upon dead animal matter at the 

 first moment of decay, and, in very hot weather, almost immediately 

 after life has ceased. Soon after these come the carrion-beetles, the 

 Silpha) and Xecrophori, whose larvic, like the maggots of the tlesh-rties, 

 are seen revelling in the putrescent matter at the most offensive stage 

 of decomposition. When the softer i)arts have been devoured and only 

 the osseous and ligamentary portions remain, other families of scaven- 

 gers succeed, namely : the skin-beetles^ T>ermesUdic^ and the bone-beetles, 

 JS'ecrohii and Ifitidula', which adhere to the dried carcass as long as any 

 vestige of animal matter remains. 



The scavenger-beetles, with a few exceptions, are readily distinguished 

 from the other pentamerous Coleoptera by the form of their antenna', 

 which, in the great majority, are strongly clavate, and sometimes capitate 

 or knobbed. 



The number of joints in the tarsi are much more variable in this than 

 any other tribe or section ; and though the larger species very uniformly 

 possess five joints in all the tarsi, in many of the very small species one 

 of the joints, especially in the iiosterior tarsi, is either rudimental or 

 wanting. The place of these insects in the system has to be determined 

 therefore by the examination and collection of their other characters.* 



''' See suggestions on pages 30 to 34. 



