INTRODUCTION. 
67 
Asellus and Limaeodes Tesludo J, they are entirely 
wanting, their place being supplied by a number of 
small simple tubercles. The larrm of a great pro- 
portion of the largest and most conspicuous of oiir 
native moths are provided with ten prolegs, like 
those of butterflies, and placed in the same order. 
In many others there are only eight, either one of 
the abdominal pairs, or the anal one, being absent. 
When the latter is the case, the hinder extremity 
of the body sometimes bears two caudal appendages 
(as may be seen in the caterpillars of the Puss and 
Lobster moths), -vvith the free motions of which a 
pair of anal legs would probably interfere. Many 
lar\'£B possess only six prolegs, others four, and a 
few of the smaller kinds merely a single pair, attached 
to the anal segment. Such as have a considerable 
number of intermediate legs generally keep their 
body, when walking, parallel wth the plain of posi- 
tion, and advance by the rapid and successive motion 
of each segment, as if, as has been happily remarked, 
a wave were flowing over or pen-ading their bodies. 
But such a mode of locomotion evidently cannot take 
place when most or all of the abdominal segments 
are ndthout legs, as is the case with some of those 
just mentioned. These accordingly adopt a different 
method, by means of which they are enabled to 
move about with ease and celerity. They first fix 
their prolegs to the plain of position and stretch the 
body forward to its full extent ; then laying hold 
\\dth the anterior legs, the tail is let free and dra^vn 
towards the head, the intervening portion of the 
