i 1 8 
INTRODUCTION TO 
described, but many instances of tbe contrary will be 
afterwards adduced. A range, or a double range of 
spines on tbe underside is frequently observed, and 
when these are absent, their place is often supplied 
by a fringe of hair or strong cilia. 
The next portion of the leg is the tibia or shank, 
which, when the insect is in motion, usually forms 
an angle with the thigh. It is connected with the 
latter by that kind of articulation called ginglymus. 
Although frequently as long as the thigh, it is com- 
monly much more slender. With respect to form, 
it is, for the most part, slender at the base, and gradu- 
ally increases in thickness to the apex ; in many in- 
stances, however, it is of the same thickness through- 
out. It is often compressed, arched, or flexuose, 
assuming the latter form to adapt itself to the ine- 
qualities of the thigh, when it requires, as is fre- 
quently the case, to be closely applied to that part. 
A transverse section is most frequently triangular ; 
sometimes quadrangular or round. The variations 
in other respects which tibite undergo, are too 
numerous to be specified in this place ; but one 
character is so conspicuous as to claim some atten- 
tion even in the most general view of their structure, 
namely, the teeth, spines, and spurs with which they 
are so frequently armed. The teeth are most re- 
markable in the fossorial species, and are usually 
largest in the anterior tibiae ; when very prominent, 
the part in question is often said to be palmated. The 
spines are either processes of the horny substance, 
or they are articulated., and have a free motion ; 
