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 Rutelidcc, which in New 
Holland has a representative, as to form, in one of the 
Cetoniada {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 Carabidce 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 line, — 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 Cicindela are aided by Manticora ; in North 
America, the Silphidce by a new group, the type of which 
is Silp/ia 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./. 6.) belong to this genus. 
b Linn. Trans, xii. t. xxii./. 2; t. xxiii./. 7- 
