34 THE ORDEll OF COLEOPTERA. 



have a part of these joints widened but uot bilobed in the males, but 

 here it is a sexual distinction, and is confined to the anterior feet. 



These small Pentamera, with variable tarsi, almost always have 

 strongly clavate autenniie, except the Stai)hylini(Ue, and these are dis- 

 tinguished at once by their short wing-covers. The true Tetramera, on 

 the contrary-, have the antennte liliform, or at most slightly and gradu- 

 ally enlarged toward the tip, except the snout-beetles {CuycuUoniike), 

 and these are readily known by their elongated rostrum. 



If, then, the student have in hand a small beetle W'hose place in the 

 system he cannot determine witii certainty, from the number of tarsal 

 joints, let him first observe whether these joints are slender and sim- 

 ple or dilated and brush-like beneath, with the last joint but one deeply 

 notched or bilobed ; and then let him examine the antenna?, and observe 

 whether they are slender and filiform, or whether they are decidedly 

 enlarged at the end, either gradually (clavate), or abruptly (capitate). 



1. If the tarsi arc simple and the antennw Jiliform, the species may 

 belong to some one of a num))er of diverse families (Carahidw, Elater- 

 idce, MordelUd(s, Melandryidw, Cistelida', and a few smaller families) ; 

 but the beetles with this combination of characters are rarely of very 

 small size, and they are, thereibre, the more easily determined by their 

 other characters. 



2. If the tarsi are simple and the antenmc clavate or capitate, the in- 

 sect may be referred, with very few exceptions, to some one of the fami- 

 lies of scavenger beetles in the pentamerous section. This rule embra- 

 ces a large proportion of very small- sized beetles, and will, therefore, 

 be found of great use to the student in narrowing the field of his 

 inquiry. A few apparent exceptions exist in the heteromerous families 

 of DiaperidiT2 and Tenebriouida^, but the former can be usually distin- 

 guished by their perfoliate anteunte, and the autenmie of the Teuebrio- 

 nidse are usually so slightly enlarged toward the tip as scarcely to be 

 entitled to the name of clavate. Other partial exceptions are found in 

 the family of Scolytidre, or short horned wood-borers, all of which have 

 strongly clavate antenna?, and some of which have simple tarsi 5 but 

 many of them have the last joint but one slightly bilobed. 



3. If the tarsi are dilated and hilohed and the antenmv filiform, the in- 

 sect belongs to the fiimily of long-horned borers (Ceramhycida% or to 

 that of the plant-beetles proper (Chrysomelidce, etc.) The tarsi thus 

 formed are almost always spongy on the under side. Only a fe.w par- 

 tial exceptions to this rule are found, and these are in the heteromerous 

 families of Oi^demerida?, Anthicida?, and a few others ; but in these the 

 tarsi are usually but slightly dilated, and but little, or not at all, spongy 

 beneath. 



