. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 442 MOTION. perfect insect, which support the three first rings of the trunk. In many larvae there are no organs of locomotion, whilst others are furnished with a variable num- berof rudimental legs, presenting differently constituted organs for progression. Most of the larvae of the Lepidoptera have ten pair of these pro-legs, respectively arti- culated to the sixth, seventh, eighth, ninth, a and anal segments of the body. One family, the Lophyrus, has sixteen pro-legs. Others, as the Stylotoma, have fourteen, and the T
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 442 MOTION. perfect insect, which support the three first rings of the trunk. In many larvae there are no organs of locomotion, whilst others are furnished with a variable num- berof rudimental legs, presenting differently constituted organs for progression. Most of the larvae of the Lepidoptera have ten pair of these pro-legs, respectively arti- culated to the sixth, seventh, eighth, ninth, a and anal segments of the body. One family, the Lophyrus, has sixteen pro-legs. Others, as the Stylotoma, have fourteen, and the Tenthredo twelve. The perfect legs move (according to Kirby and Spence) in the same order as in the imago state; the pro- legs serve not only to raise and support the abdominal and caudal segments of the trunk, but also to assist in grasping objects in the plane of motion, and in urging the centre of gravity forwards. When the head and thoracic segments are fixed, the body and tail are drawn forwards ; the trunk is arched in the vertical plane; the tail being fixed, the pro-legs are advanced successively in pairs, beginning from the anal segment; the body is then extended, and the head advanced to take a new position; a conspicuous undulation of the body is produced, proceeding from the caudal to the cephalic seg- ments. The larva of the Ant-lion (Myrmeleon) moves in a backward direction, even after the removal of its legs. Many larvae, such as the Caterpillar of the Hawk-moth, move with ex- treme slowness, whilst others possess consi- derable powers of locomotion, as the Apotela Leporina, which has received its appellation from the rapidity of its movements. But of all terrestrial larvae, the most remarkable for their attitudes and motions are the Geometrae. The true Geometrae have only two anal, and two in- termediate pro-legs ; with these they grasp any object so as to fix the anal extremity : the trunk, with the head, is then extended, elevated, and inclined from the horizo
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