200 TRANSACTIONS OF THE ILLINOIS 



with an angulated projection on the margin. Most of the species form 

 galls on the leaves of plants, some also attacking the roots. 



As a full account of the Grape Phylloxera, the only very important 

 species, has been published in these Transactions, from Prof. Riley's 

 Report, I will simply give the following catalogue of the American species 

 as I find it in that author's Seventh Report. 



86. P. vastabrix, Planch., (^Pemphigus vitifoHcE, Fitch). The Grape Phyl- 



loxera. 



Forming galls on the leaves and swellings on the roots of grape-vines. 



87. P. Rileyi, Licht. The Oak-leaf Phylloxera. 



Living on the under side of the leaves and hibernating on the stems 

 of the white, swamp white and iron oaks {^Qiiercus alba, bicolor and 

 obfusiloba). 



88. P. carycefo/m, Fitch. The Phylloxera of the Shag-bark Hickory-leaf. 



Forming conical galls, which open on the summit, on the upper side 

 of the leaves of the shag-bark hickory (^Carya alba). 



89. P. carycBcaulis, Fitch. 



Forming elongate, rather irregular, but generally ellipsoid, smooth, 

 green swellings, of large size, on the petiole or stalk of the leaves oi ca7ya 

 alabra and amera, the galls opening in a small nipple on the under side. 



90. P. carycevenm. Fitch. 



Forming plaits in the veins of the leaves of Carya alba, which plaits 

 project upward from the surface in an abruptly elevated keel on the upper 

 side of the leaf, the mouth opening on the under side, the lips of which 

 are woolly. 



91. P. carycB-semen, Walsh. 



Forming fuscous, minute, sub-globular, seed-like galls on the upper 

 side of the leaves of the pignut hickory (^Cary a glabra), which open in a 

 small nipple on the under side. 



92. P. carycB-globuli, Walsh. 



Forming hemispherical galls, about the fourth of an inch in diameter, 

 on the upper surface of the leaves of Carya glabra and alba; the galls 

 rather flat below, where they open with a slit. 



93. P. spinosa, Shimer. 



Forming large, irregular galls, covered with spines, on the petiole of 

 the leaves of Carya a?nara (bitternut hickory), the galls opening be- 

 neath with an irregular sinuate slit. 



