244 DAVENPORT ACADEMY OF SCIENCES. 



26. Large, oval, smooth; growing upon the petioles. A slight central 



depression, covered with short hairs. Length about 20™™-,' diam- 

 eter about 10"""- Ph. subelliptica Shimer. 



n. Galls more or less globular or irregular, terminating in a tooth-like 

 nipple. 



27. Growing on tender twigs, petioles or ribs of leaves, often confluent. 



Smooth. Diameter 2-8™™- Ph. perniciosa Pergande, n. s. 



in. Galls more or less reniform. Opening when mature in a transverse 

 slit. 



28. Growing on the petiole or midrib of the leaves, the transverse slit 



dividing the gall in two halves Ph. c.-ren Riley. 



Phylloxera cary^caulis Fitch. 



PI. VIL, fig. 40 ; PI, XIV., fig. 106 ; carycecaulis; 

 PI. VII., figs. 41-42 ; PI. XIV., fig. 107 ; var. magna; 

 PL VIII., figs. 43-44; PI. XIV., figs. 108-114; var. spinosa, 

 PI. XVI., figs. 134-127 ; var. spinosa. 



Pemphigus caryacaulis Fitch. Third Rep. Nox. and Ben. Ins. of 



N. Y., p. 126 and 163. 

 Dadylosphcera carycE-magnum Shimer. Trans. Am. Ent. See, 2, 



P-39I- 

 Dactylosphcera spinosum Shimer. Trans. Am. Ent. See, 2, p. 397. 

 Phylloxera carycecaulis Riley. Seventh Rep. Nox. and Ben. Ins. 



of Mo., p. 117. 

 Phylloxera carycecaulis Thos. Eighth Rep. Nox. and Ben. Ins. of 



Ills., p. 160. 



Up to the present time these three forms of galls have been 

 considered as quite distinct species on account of their dis- 

 similarity, two of them being smooth and the other more or less 

 profusely covered with fleshy spines. But a careful study of the 

 architects of these forms forces the conclusion that they are 

 identical, there being no tangible characters by which to separate 

 them. The spiny form of gall always grows upon trees with 

 pubescent leaves, such as Hicoria tomentosa, while the smooth 

 forms are always found upon trees with smooth leaves, such as 

 Hicoria glabra, amara and probably other species. 



The typical form, growing upon the young and succulent 

 limbs, petioles or the midrib of the leaflets of Hicoria-glabra, occurs 

 over the eastern half of the United States. 



