II inter idee."] CLAVICORNIA. 197 



HISTERID.E. 



This family, according to the Munich catalogue of 1868, contains 60 

 genera and 1150 species ; since that time, however, a large number of 

 species and about 20 genera have been added through the researches of 

 Schmidt, Lewis, and other Coleopterists who have especially studied the 

 group ; as a rule the members of the family are conspicuous for 

 their smooth shining appearance, and the total want of pubescence; some 

 few genera, however, have the outer skeleton very opaque and are strongly 

 sulcate ; the chief characters of the family are as follows : antenme 

 short, geniculate, capable of being retracted, club distinct and com- 

 pact and as a rule received into cavities of the prosternum ; thorax 

 closely applied to elytra ; prosternum frequently lobed in front ; coxal 

 cavities open behind ; mesosternum variable in shape, metasternum 

 very large; elytra truncate behind, leaving the pygidium and propygidium 

 uncovered ; a-bdomen with five free ventral segments ; legs short, capable of 

 being retracted closely underneath body, tarsi short and slender and in most 

 genera received in grooves on the anterior face of the tibiae, usually 

 5-jointed, but in one or two genera the posterior pair are 4-jointed ; 

 intermediate and posterior coxae widely separated. 



The greater number of the species are found in dung and carcases, 

 but the Hololeptina, which are remarkable for their flat appearance and 

 prominent head, as well as for the peculiar structure of their mandibles 

 and maxillas, live under the bark of trees ; of these we possess no repre- 

 sentatives, but one or two of our genera, as Paromalus and Abrceus, occur 

 in damp rotten wood, and another, Teretrius, appears to be parasitic on 

 certain wood-feeding beetles ; one or two species are found exclusively 

 in ants' nests. 



The species as a rule are round or oval or more or less oblong, rarely 

 cylindrical, of a unicolorous shining black or brownish colour, sometimes 

 greenish or bluish, and occasionally metallic, with more or less distinct 

 striation on the elytra ; sometimes the elytra are marked with bright 

 red spots or patches. 



It may perhaps be observed that there is considerable difference among 

 the writers on this family as to its generic classification. 



The Inrvso of the Histeridse are distinguished by the absence of ocelli, the soft- 

 ness of their integument, the upper surface of the abdomen being often much wrinkled, 

 the very short legs which in Sister are not visible from above, and the broad ninth 

 segment of the abdomen which bears two short, 2-jointed cerci ; they are furnished 

 with large and powerful piws, and are carnivorous and very voracious. Our British 

 genera may be distinguished as follows : 



I. Upper surface not costate (in the European species).* 

 i. Pi-osternura lobed in front, covering under-side of head. 



* Hister costatus from Mexico has the opaque exoskeleton and costate sculpture 

 of Onthophilus, but it is at present the only species known that presents this pecu- 

 liarity. 



