PERIODICAL CICADA
the insect humps its back (4), the skin splits along the midline of the thorax (.5), the rupture extending forward over the top of the head and rearward into the first seg- ment of the abdomen. A creamy white back, stamped with two _large .let-black spots, now bulges out ((5, 7); next comes a head with two brilliant red eyes (8); this is followed by the front part of a body (9) which bends backward and pulls out legs and basés of wings. Soon one leg is free (`'o), then four legs (`'`'), while four long, glistening white threads pull out of the body of the issuing creature but remain attached to the empty shell. These are the linings of the thoracic air tubes being shed with the nymphal skin. Now the body hangs back down, when all the legs come free (`'2), and now it sags peril- ously (C?') as the wings begin to expand and visibly lengthen. Here another rest intervenes; perhaps twentv-five min- utes may elapse, while the sort new creature, like an in- verted gargoyle supported only by the rear end of its body, hangs motionless far out "fro?{? the split in the back of the shell. Now we understand why the nymph took such pains to get a firm anchorage, for, should the dead claws give way at this critical stage, the resulting fall most probably «ould prove fatal. The next act begins abruptly. The gargoyle moves again, bends its body upward ("4), grasps the head and shoulders of the slo'ugh (*'5), and pulls the rear parts of its body free from the gaping skin (,,6). The body straighten?" and hangs downward (`'7)- At last we be- hold the free imago, hOt ver mature but rapidly assum- ing the characters of an adult cicada. The new creature hangs for a while from the discarded shell-like skin, clinging by the front and middle legs, sometimes by the first alone; the hind ones spread out sidewavs or bend against the body, rarely grasping the skin. The wings continue to unfold and lengthen, finally hang fiat, fully formed, but soft and white (`'N). 14ere the creature
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INSECTS
