CIIIIYSOMELIDAE. 335 



Metasternum either long or short side pieces. 



Elytra usually covering the dorsal segments, sometimes 

 leaving the pygidium exposed (Camptosomes); rarely (in 

 some genera of Gallerucini) smaller, and not covering the 

 greatly enlarged female abdomen; epipleurte usually dis- 

 tinct. 



Abdomen with five ventral segments, varying in pro- 

 portion. 



Anterior cox£b varying in form and position ; middle coxas 

 either contiguous or separate; hind coxas transverse, con- 

 tiguous, or separated, not laminate. 



Legs usually short, hind thighs frequently enlarged, and 

 in some groups of Gallerucini saltatorial ; tibic^ never serrate, 

 usually without spurs; tarsi with the joints 1-3 usually 

 broad, covered beneath with a brush of hair; 3d frequently 

 bilobed ; 4:th anchylosed closely to the 5th, which has two 

 equal claws of variable form. Rarely (liaemonia, and Ste- 

 nopodius) the tarsi are narrow, and the last joint is very long, 

 with large simple claws, suited to grasp subaquatic plants 

 on which they live. 



Tills family is an immense complex, developed to the largest 

 extent in the tropics, though by no means without a respectable 

 representation in temperate and boreal regions. As the function 

 of the CerambycidiE is to hold the vegetable world in check by 

 destroying woody fibre, the BrucliidiB effect a similar result by 

 attacking the seeds, and the Chrysoraelidye by destroying the 

 leaves. As the cellular and succulent leaved plants have suc- 

 ceeded the drier and more ligneou^^ forms of early geological time, 

 so have the Chrysonielidte probably attained their liighest devel- 

 opment in the more recent periods, and it is therefore interesting 

 to note that their relations with Rhynchophora are proportion- 

 ately more feeble than those of the other two families above men- 

 tioned. 



Among the species of this family are to be found some of the 

 most formidable Coleopterous pests of Agriculture; but with few 

 exceptions they belong to the tribe Gallerucini. A notable ex- 

 ception, however, is the Doryphora decemlineata, the world- 

 known Colorado potato-bug. 



In order to make the tables of tribes and genera more intelli- 

 gible to the student, it will be proper to define the different forms 

 of tarsal claws, which liave been used in the classification of this 

 very troublesome family. 



