54 THE ORDER OF COLEOPTERA. 



A. Middle and hind tarsi with the first four joiuts short ,- tlie last often as long as all the others: 



body oblong ; thorax furrowed, and narrower than the elytra ; size small Helophokus 



A A. Midflle and hind tarsi with second joint elongated, first very short ; body o\al ; thorax as 

 wide at base as elytra. 

 B. ^Metasternum keeled and prolonged backward into a sharp spine ; tarsi flattened ; size large 



or very large H yduoi'HILUS . 



B B. Metasternura not prolonged ; tarsi not compressed ; size small or voiy small. 



C. Hind tibia; and tarsi ciliate ; soutollum elongated Beuosus. 



C C. Hind tibise and tarsi not ciliate ; sciitellum regularly triangular Hyuhohius. 



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

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



TiiiBE IV. 



LAND SCAVENGER BEETLES. 



Putrivora terrestria, Necrophaga partly, Latreille. 



This tribe embraces au extensive series of useful scaveugers, whose 

 office it is to hasten the decomposition and removal of dead organic 

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

 composing animal substances. Some of the smaller species are found 

 under the bark of dead trees ; whilst others feed upon fungi, especially 

 those which grow upon decaying trees. The only other insects which 

 can be compared with these in usefulness as s(!avengers, is the extensive 

 family of Mtiscidcc, in the tAvo- winged flies. It is interesting to observe 

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

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

 flies, deposit their eggs or J1i/-hlou\s upon dead aiiinuil 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 Necrophori, whose larvie, like the maggots of the flesh-flies, 

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

 of decomposition. AVhen the softer parts have been devoured and only 

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

 gers succeed, namely : the skin -beetles, Dermestidw, and the bone- beetles, 

 Necrohii and Nitidula', 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 clavale, 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 posterior tarsi, is either rudi mental 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 suifgeBtious on pages 30 to 34. 



