“The muscles proper to the prothorax consist of four pairs, by which it is united to the succeeding segments. The first of these, the superior retractor, _retractor prothoracis superior_ (_h_), arises by a broad, fleshy head from the anterior external margin of the pronotum, and passing directly backwards is inserted by a tendon into the prophragma, a little on one side of the median line. The next muscle of importance, the inferior retractor (_i_), arises from the anterior border of the medifurca, and is united to the posterior of the antefurca, thus forming with that muscle part of the great recti of the larva. This muscle must be considered as the proper depressor of the prothorax. The _elevator prothoracis_ (_k_) is narrow, pyramidal, and arises fleshy from the lateral surface of the prophragma. It passes downwards and is attached by a narrow tendon to the superior portion of the antefurca. The _rotatores prothoracis_ are the largest of all the muscles of this segment. They arise, one on each side (_l_), by a narrow head from the posterior part of the pronotum, and passing beneath the prophragma are considerably enlarged and attached to the tegument between the two segments, and also to the anterior portion of the mesothorax. The remaining muscle proper to the prothorax is the closer of the spiracle, an exceedingly small muscle not shown in the drawing. “The other muscles of this segment are those of the legs, which are of considerable size. There are three distinct flexors of the coxa (_m_, _n_, _o_). The first of these arises from the superior lateral border of the pronotum, the second from the superior posterior border, the third from the sides of the prothorax, and the fourth a little nearer posteriorly, and the whole of them are attached by narrow tendons to the sides of the coxa. But there is only one extensor muscle to this part. In like manner, the extensor of the trochanter is formed of three portions (Fig. 233, _a_, _b_, _c_); but there is only one flexor (_d_), and one abductor (_e_). In the femur, there is one extensor (_f_),—a long penniform muscle that occupies the superior part of the thigh, and is attached by a tendon to the anterior-posterior margin of the joint formed by the end of the tibia. There is also but one flexor (_g_) in the femur, which, like the preceding muscle, is penniform, and occupies the inferior portion of the femur, and its tendon is attached to the inferior border of the tibia. In the tibia itself there is also one flexor and one extensor. The _flexor_ (_i_) occupies the superior portion of the limb, and ends in a long tendon (_l_) that passes directly through the joints of the tarsus, on their inferior surface, and is attached to the inferior margin of the claw (_g_). The _extensor_ (_h_) occupies the inferior portion of the tibia, and is shorter than the preceding muscle, like which it ends in a long tendon that