86 
NATURAL HISTORY 0 Y 
mals.* On many, taking her rule and compassesy 
she draws with precision mathematical figures 5 
points, lines, angles, triangles, f squares, and circles” 
Some extensive groups are characterized by the pre- 
valence of certain hues, bestowed on them probably 
as a means of concealment from enemies, by assi- 
milating them to the objects by which they are us- 
ually surrounded, or in subserviency to some par- 
ticular purpose in their economy. The prevailing 
colour among beetles of obscure haunts — such as 
burrow in the earth, or pass the greater part of their 
lives under stones (the Geodephagi of some modern 
systematic writers), as well as those destined to fa- 
cilitate the decomposition and dispersion of putres- 
cent and excrementitious substances — is black or 
brown. The water-beetles (Dytiscida) are almost 
uniformly brownish black, inclining to olive, and 
frequently variegated with streaks and spots of dull 
yellow. The rostrated beetles, or weevils ( Curcu - 
lionidce), present some of the most highly adorned 
examples of insect life ; and in them also a curious 
instance is observable of change in colour accom- 
panying dissimilarity of habit. Numerous kinds of 
these insects occur among loose earth and sand, or 
under stones, and these are almost invariably of 
sombre hues, and destitute of ornament : an exten- 
sive division of the same tribe inhabit trees and 
shrubs, and they are remarkable for displaying the 
Ptinus imperialism Linn. 
+ Trichius delta , Fab. 
