t>ERGANtlE — KORTtI AMERICAN PttYtLO^CERlN/t. 243 



without avail. Unfortunately nearly all the trees on which the 

 galls used to be plentiful had been cut down, leaving but a few 

 small shrubs in that particular locality, with still fewer galls on 

 some of the leaves. These galls were also extremely scarce on 

 trees in the woods some distance to the north, in all of which the 

 usual apterous forms and some eggs were present, though not a 

 single one of the winged migrants. That this form, after a 

 shorter or longer interval must exist, seems quite plain, while 

 otherwise the species is doomed to become extinct, since the mi- 

 gration of some of the apterous forms from tree to tree, especially 

 if such trees should grow at some distance from each other, must 

 naturally be rather slow and uncertain. I take it, therefore, for 

 granted that the spread of this species depends, as in other species, 

 on a winged migrant, which sooner or later will be found. 



Group IV. 

 Twig or Petiole Galls. 



This group comprises a series of more or less closely related 

 galls, growing principally on the youngest twigs and petioles. 

 Some of them resemble each other so closely that it is frequently 

 difiicult to separate them, particularly after they have become 

 dry, though the insects producing them often differ markedly. 



For convenience these galls may be divided into three sections. 



I. Galls more or less globular. Orifice completely closed when young ; 

 splittiug into j-6 orinore irregular bracts when mature and leaving an 

 irregular opening. 



22. Globular or oval ; often more or less conical ; spiny or smooth accord- 



ing to the tree on which they grow, and more or less confluent. Size 

 varying from 5-25™"- Ph. caryacaulis Fitch. 



23. Globular; covered densely with long and fleshy filaments. Size 



c_j=mTii. Ph. spinuloides Pergande, n. s. 



24. Size medium ; growing in larger or smaller clusters, and apparently 



deformations of the flower and leaf-buds. Splitting when mature 



into four or more broad bracts. Surface smooth. Size 3-15™™- 



Ph. devastatrix Pergande, n. s. 



25. Size medium ; smooth ; growing in clusters ; usually with a short, 



stout, nipple-like projection on one side. Diameter 5-10™™- 



Ph. georgiana Pergande, n. s. 



