THE SUSPENSORY MUSCLES IN A TIPULID LARVA,

There are three pairs of suspensory muscles in the larva of Tipula abdominalis which originate dorso-laterally between body segments one through four and insert laterally along the mid-gut and on the mid-portion of the Malpighian tubules. Cytologically these muscles resemble body wall muscles more than gut muscles. In the living animal, the muscles probably take up slack and keep the gut and Malpighian tubules from being displaced unduly. Although the existence of suspensory muscles in some insect larvae has been recognized for some time, few descriptions of these muscles have actually been published. Lyonet (1762) was the first to describe such muscles, in the carpenter moth, Cossus cossus. He observed seven pairs of these muscles which extended from intersegmental portions of the body wall to various places on the mid-gut, hind-gut, Malpighian tubules, and silk glands. He called these "trunk " muscles. Much later, a second observation of such muscles was made in the silkworm, Bombyx mori. Tanaka (1911) described nine pairs of muscles which he called "dermo-visceral " muscles. They originated on the body wall between segment