GEOGRAPHICAL DISTRIBUTION OF INSECTS. 497 
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 Cara- 
bide may in the same country be said to have a represen- 
tative in the remarkable heteromerous genus Adelium®*, 
which is altogether an analogy. Others are representa- 
tive only in their function. The general function of in- 
sects is to remove nuisances and to check redundancies,— 
the saprophagous tribes do the one, and the thaleropha- 
gous the other. In going from the poles to the line,—in 
proportion 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 unzversal Cicindele are aided by Manticora ; in North 
America, the Silphide by a new group, the type of which 
is S. Americana; in South America, Copris by Phanaus 
M‘L. Again: Colliuris and Drypta of the old world, 
in the new give place to Eutrachelus and Agra. ‘The 
honey and wax of Europe, Asia, and Africa, is prepared 
by dees congenerous with our common hive-bee (Apzs 
Latr.); while in America this genus is not found as a na- 
tive, but is replaced by Melipona and Trigona®; and in 
New Holland by a still different but undescribed type. 
The Melolonthide and Rutelide of the old and new 
world appear to have their work done in that country by 
the brilliant and numerous Anoplognathide. The Rhi- 
2 Linn. Trans. xii. t. xxii. f. 2; ¢. xxii. f. 7. 
> Latreille, Géograph. &c. 10. 
VOL. IV. 2K 
