INTKODtrCTION. 
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body being bent upwards into a loop or arch. Every 
progressive movement is effected by a repetition of 
tbe same manoeuvre, and the ground is thus traversed 
by regular and measured steps, each of which is 
nearly equal to the length of the insect’s body. 
These peculiar attitudes have caused the catcrpilkvrs 
to be termed loopcrs and geometers ; and as they 
possess the power, from the great strength of their 
muscles, of fixing themselves by the hinder legs 
to a branch, and stretching out the body stifSy 
into the air, a position which they often maintain 
immovably for a length of time, they are likewise 
knorvn by the name of surveyors. Tlie kind of 
locomotion just described is best exhibited by such 
lairae as have only two or four prolegs, but it is 
likewise seen in those that have six, and occasionally 
even in species furnished rnth the full compliment 
of ventral legs. 
In the colour of their bodies these caterpillars 
are as gre.atlj' diversified as in their other properties. 
Such as live in the interior of trees, mid in places 
where they are little exposed to the influence of 
light, are frequently of a dingy white or yellowish 
bronn colour; but the kinds which frequent the 
foliage of plants, constituting by far the largest 
proportion, are often ornamented wth the most 
vivid and varied tints. Eeaiunur asserts that they 
exhibit examples of every knonn colour, besides 
an infinite variety of shades, of which it would be 
difficult to find the like elsewhere. Some are of 
one uniform hue, but the mfgority are adorned 
