insects. 
1 
or breathing-holes, distributed in a series or row 
on each side the whole length of the abdomen 5 
and these spiracles or breathing-holes are supposed 
to communicate with a continued chain, as it were, 
of lungs, or at least of parts analogous to them, 
distributed throughout the whole length of the 
body. The head is furnished with a pair of what 
are termed Antennce or horns, which are extremely 
various in the different tribes, and which, by their 
differenees of structure form a leading character in 
the institution of the Genera or small assortments 
into which Insects are distributed. 
Among the older writers on Natural History, 
and even among some of the more modern, several 
animals are called by the name of Insects, which, 
in reality belong to a very different tribe of beings, 
as Snails, several kinds of Worms, and the smaller 
•animals in general. What are termed Animal- 
cules in modern Natural History are also fre- 
quently confounded with insects, though in reality 
belonging to the very different tribe of Vermes or 
Worm-Like Animals. 
It is not intended at present to enter, with any 
degree of minuteness, upon the anatomical de- 
scription and philosophic history of Insects; since 
this has long ago been elucidated in almost all its 
branches by the labours of Swammerdam, Reau- 
mur, Roesel, and many other authors : to relate 
therefore what has been so often described may be 
thought in a great degree unnecessary: yet, on 
the other hand, it may with equal propriety be 
observed, that few who have not been particularly 
