described, but many instances of the contrary will be afterwards adduced. A range, or a double range of spines on the 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 commonly much more slender. With respect to form, it is, for the most part, slender at the base, and gradually increases in thickness to the apex; in many instances, however, it is of the same thickness throughout. It is often compressed, arched, or flexuose, assuming the latter form to adapt itself to the inequalities of the thigh, when it requires, as is frequently 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 tibiæ undergo, are too numerous to be specified in this place; but one character is so conspicuous as to claim some attention 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 remarkable in the fossorial species, and are usually largest in the anterior tibiæ; 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;
