DIGESTIVE SYSTEM OF PERIODICAL CICADA. 221 



function. It certainly becomes modified in later life but it is 

 at all times a part of the digestive system. This condition which 

 is easily observed in sections makes unnecessary the postulation 

 of any secondarily derived function on the part of this organ. 

 The method of gross dissection, then, is inadequate to explain 

 the conditions found. 



BIBLIOGRAPHY. 

 Berlese, A. 



'09 Gli Insetti. 

 Dufour, L. 



'33 Rech. anat. et physiol. des Hemipteres. 

 Hickernell, L. M. 



"20 Ann. Ent. Soc. Am., Vol. XIII., No. 2. 

 Kershaw, J. C. 



'13 The Alimentary Canal of Plata and other Homoptera. Psyche, Vol. XX., 



No. 6. 

 Licent, E. 



'n Signification de la dilation proventriculaire chez les Homopteres superieure 



(Hem.). Bull, de la Soc. Ent. France. 

 Marlatt, C. L. 



'98 U. S. Dept. Ag. Div. Ent. Bull., 14, N. S. U. S. Dept. Ag. Bur. Ent. 



Bull., 71- 

 Snodgrass, R. E. 



'21 Smithsonian Report for 1919, pp. 381-409. 



