GEOGRAPHICAL DISTRIBUTION OF INSECTS. 509 



function / and others in both. I shall give some instances 

 of each. In Brazil there is a group of petalocerous 

 beetles (Chasmodia), one of the Rutelidtf, which in New 

 Holland has a representative, as to form, in one of the 

 CetoniadcB (Schizorhina a ), which, having soft mandibles, 

 must have a different function : it is to be observed, 

 however, that these insects appear to approach each other 

 in the series of affinities. Again, the Cardbidce may in 

 the same country be said to have a representative in the 

 remarkable heteromerous genus Adelium b , which is al- 

 together an analogy. Others are representative only in 

 their function. The general function of insects is to re- 

 move nuisances and to check redundances, the sapro- 

 phagous tribes do the one, and the thalerophagous the 

 other. In going from the poles to the linej in propor- 

 tion as the heat increases, the quantum of work of both 

 kinds increases ; and new forms are either added to the 

 old ones, so as to increase their momentum; or new 

 ones, more powerfully talented, replace the old ones, and 

 act in their stead : thus we see a gradual and interesting 

 change take place in proportion as we approach the 

 maximum of heat and of insect population. At the Cape, 

 the universal Cicindelce are aided by Manticora; in North 

 America, the Silphidteby* new group, the type of which 

 is Silpha Americana (Necrophila, K.MS.) ; in South 

 America, Copris by Phanceus. Again: Colliuris and 

 Drypta of the old world, in the new give place to Cte- 

 nostoma and Agra. The honey and wax of Europe, Asia, 

 and Africa, is prepared by bees congenerous with our 



a Cetonia atropunctata and Brownii of Linn. Trans, (xii. 464. 

 t. xxiii.y. 6.) belong to this genus. 



b Linn. Trans, xii, t. xxii./. 2; t. xxiii./. 7- 



