92 



INTRODUCTION". 



on larva; of the Ohrysomelid genus Agelastica. while II ister pustu- 

 losis attacks caterpillars of Agrotis. 



A certain number of genera (e. g. Hetcerius and Myrmetes) are 

 only found in ants' nests ; while others are occasionally found 

 associated with ants; others again (Hesperodromus, Disccselis, 

 Termitoocenus, etc.) live with Termites ; their relations, however, 

 to these insects are uncertain. 



The larvae of several genera are well known ; they are distin- 

 guished by the absence of ocelli, the softness of their integument, 

 the upper surface being often much wrinkled, and the short but 

 well-marked two-jointed cerci at the apex of the abdomen. The 

 larva of Bister unicolor is a broad flabby repulsive-looking insect 

 with large jaws and extremely short legs, not visible from above ; 

 in Platysoma the form is narrower and more parallel and the legs 

 are longer. These larvse are carnivorous and very voracious. 



In 1853-1862 the Abbe de Marseul monographed the family, 

 but our knowlege of the group has since then been very much 

 increased, in great measure through the exertions of Mr. George 

 Lewis, who is at present the chief authority on the Histeridte. 



Erichson in 1834 proposed three divisions of the family : — 



1. Head porrected. 



2. Head retracted into the prothorax ; prosternum with a 



plate in front covering the throat, separated by a suture. 



3. Head retracted into the prothorax ; prosternum without 



a separated plate covering the throat. 



Lacordaire (Gen. Col. h, 1854, pp. 248-252) follows Erichson, 

 but only adopts two divisions : the Holoeeptides with the head 

 porrected, and the Histerides with the head retracted ; and he is 

 followed by Leconte and Horn (Classification Col. North. Am. 

 ]). 144). Jacquelin Duval (Gen. Col. Eur.ii, 1857-1859, pp. 119- 

 121 ) practically adopts the whole classification of Marseul, so far 

 as the European Eauna is concerned, and gives an excellent 

 table of the genera. 



MarseuFs classification is as follows : — 



I. Head not retractile, horizontal, visible from under- 



neath; mouth-parts projecting beyond the front 

 of the prosternum. 



1. Mandibles projecting; clypeus not prolonged 



into a rostrum ; body more or less fiat and 

 depressed 



2. Mandibles retracted, covered by the long rostri- 



form clypeus ; body elongate, cylindrical 

 ( Trypanams) 



II. Head retractile, not visible from underneath when 



retracted ; mouth-parts covered by the prosternum. 

 A. Prosternum with a shorter or longer lobe or 

 throat-plate, separated oft by a more or less 

 distinct suture. 



IIOLOLEPTINJE. 

 TllYPANJEINiE. 



