90 
INTRODUCTION TO 
the larvce. The following figures afford examples of 
these different kinds of pups, the numerals referring 
to the order in which they have just been named. 
On examining the interior of a pupa immediately 
or shortly after it is formed, it is found to consist al- 
most entirely of a milky fluid, which soon, however, 
acquires the consistency of pulp, when the members 
of the future insect can be detected. They are not 
long in enlarging by the absorption of the ambient 
matter, and when they acquire their full size, they 
completely fill, in most instances, the interior of the 
pupa-case. The integument, as above intimated, 
varies greatly in its consistency. In the Lepidoptera 
it acquires its rigidity from a viscous fluid, which 
oozes out from the region of the thorax, and spreads 
over the whole surface, forming a hard and varnished 
shell. The superficies is for the most part naked. 
In some cases, however, it is tufted with hairs, (as 
in Orgyia pudibunda, Leucoma Salicis ,*) occasionally 
