310 
SYSTEMATIC ARRANGEMENT 
body almost always elevated and curved in the form 
of the letter S. Additional distinctive characters 
might be mentioned, such as the form of the eyes, 
which are pretty large in pseudo-caterpillars, and 
placed one on each side of the head, while in true 
caterpillars they are small almost invisible points 
disposed in a circle ; but those already referred to 
will suffice to distinguish the two tribes. 
The body of pseudo-caterpillars is generally com- 
posed of twelve segments, but the incisures are in- 
distinctly defined, and liable to be confounded with 
the transverse wrinkles which thickly cover the 
whole surface. Many of them are marked with 
bright and varied colours, but the majority arc of 
one colour. In this respect they often uudergo a 
remarkable change after they have cast their last 
skin, the colour becoming entirely unlike what it 
was before, so that it is impossible to recognise the 
same individual. This change, indeed, extends even 
farther than to colour, for such kinds as are furnished 
with tubercles or spines in their earlier stage, lose 
them at their last moult and become smooth ; that 
of the gooseberry species, for example, loses the 
black tubercles wdiich made the surface appear as 
if ' shagreen ed. Like the flies they produce, these 
larvse are sluggish and inactive, seldom moving from 
the place where they have fixed themselves, unless 
wiien requiring an additional supply of food. When 
not engaged in feeding, or when apprehensive of 
danger, they roll themselves into a circle, sometimes 
with the tail elevated in the centre. The greater 
