No. 428.] THE METAMORPHOSIS OF SISYRA. 631 
4. Three Malpighian tubules are attached at both ends, 
and two are attached at one end, —all metamorphosed into 
silk glands in their middle portion. 
5. The small intestine is modified into an outlet for the 
silk secretion. 
6. The spinneret is formed from the terminal part of the 
alimentary canal. 
7. A completer account than has hitherto appeared is here 
given of the late stages of wing development, and the variations 
in venation of fifty wings are tabulated. 
BIOLOGICAL LABORATORY, LAKE FOREST COLLEGE. 

BIBLIOGRAPHY 
1771. DE GEER. Mém. pour servir à l'histoire nat. ins. Tome ii, pt. ii. 
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(2d series). Vol. xi, pp. 380. 
1844. GRUBE. Beschreibung einer auffallenden, an siisswasserschwammen 
lebenden Larve. Wiegm. Arch. f. Natu Bd. xi, pp. 331-337. 1 pl. 
2. HAGEN. Die Entwickelung und fe innere Bau von Osmylus. 
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1901. NEEDHAM. Aquatic Insects in the Adirondacks. Bulletin N.Y. 
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