STATES OF INSECTS. (Larva.) 113 
larva be of a tolerable size, distinguished at the first view. 
In those of many Dipterous insects, however, the head is 
covered with the same flexible membranous skin with the 
rest of the body, from which it is often scarcely to be di- 
stinguished. In these, except that it contains the organs 
of manducation, it wears no more the appearance of a 
head than any other segment of the body, and scarcely 
so much as the last or anal one. ‘The head of these larve 
is also remarkable for another peculiarity,—that it is ca- 
pable of being extended or contracted, and assuming dif- 
ferent forms at the will of the insect: a property which 
the head of no superior animal can boast. It is probable 
that there is a considerable variety in the shape and cir- 
cumstances of the heads of larvae; but since, with the ex- 
ception of those of Lepidoptera, they have had less at- 
tention paid to them than they deserve (indeed in a vast 
number of cases, from the difficulty of meeting with them, 
these variations, except in a few instances, have not been 
described), I will here mention a few of the most remark- 
able. The head of the young larva at its first exclusion 
from the egg is usually the most dilated part of the body, 
but it does not often continue so. In that of Cicindela 
campestris, however,—the beautiful green beetle some- 
times found in sandy banks,—and also in several cater- 
pillars of Lepzdoptera, it is much larger than any of the 
following segments*; which, in conjunction with the 
animal’s formidable jaws, gives it a most ferocious ap- 
pearance. In some lepidopterous larvee the head is of 
the same diameter with the rest of the body, but in in- 
sects in general it may, I think, be stated as less; and 
occasionally it bears no proportion whatever to it. This 
*Puate XVII, Fie. 13. 
VOL. III. I 
