THE PERIODICAL CICADA 



this garment is not a mere bag; it is provided with special 

 pouches for the appendages or a part of them (Fig. 125, 2). 

 The incased antennae and the labrum project backward 

 as three small points lying against the breast. The 

 front legs are free to the bases of the femora, though so 

 tightly held in their narrow sleeves that their joints have 

 no independent motion. The middle and hind legs are 

 also incased in long, slim sheaths, but they always adhere 

 close to the sides of the body. Thus the cicada nymph 

 newly-hatched much resembles a tiny fish provided only 

 with two sets of ventral fins, but when it gets into action 

 its motions are comparable with the clumsy flopping of a 

 seal stranded on the beach and trying to get back into 

 the water (j). 



The infant cicada knows it is not destined to spend its 

 life in the narrow cavern of its birth, or at least it has no 

 desire to do so. With its head pointed toward the exit, 

 it begins at once contortionistic bendings of the body, 

 which slowly drive it forward. By throwing the head 

 and thorax back, the antenna] tips and the front legs are 

 made to project so that their points may take hold on 

 any irregularity in the path. Then a contractile wave 

 running forward through the abdomen brings up the rear 

 parts of the body as the front parts are again bent back, 

 and the "flippers" grasp a new point of support. As 

 these motions are repeated over and over again, the tiny, 

 awkward thing painfully but surely moves forward, per- 

 haps helped in its progress bv the inclined tips of the 

 flexible eggshells pressing against it, on the same prin- 

 ciple that a head of barley automatically crawls up the 

 inside of your sleeve. 



Once out of the door no time is lost in discarding the 

 encumbering garment, but it is never shed in the nest 

 under normal conditions. If, however, the nest is cut 

 open and the hatching nymph finds itself in a free, open 

 space, the embryonic sheath is cast off immediately, often 

 while the posterior end of the insect's body is still in the 



f 221 1 



