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gif'i-ca), is most common on the red oak, but it occurs also 
on the black oak. In this gall the space between the kernel 
and the outer layer is quite densely filled with a porous 
mass, which suggests the name spongy. 
The Larger Empty Oak-apple, Holcaspis inanis (Hol- 
cas'pis i-na'nis).—There are two oak-apples which are very 
similar in structure, and which may be termed the empty 
oak-apples. In these the space between the central kernel 
Fig. 746.—Gall of Amphibolies coccineee. 
and the outer shell contains only a few, very slender, silky 
filaments, which hold the kernel in place. The larger of 
these two galls measures an inch or more in diameter, and 
is found on the scarlet oak and the red oak. 
The Smaller Empty Oak-apple, Holcaspis centricola (H. 
cen-tric'o-la), is found on the post-oak, and measures three 
fourths of an inch or less in diameter. It also differs from 
the preceding in that the outer shell is mottled. 
The Bullet-gall, Holcaspis globulus (H. glob'u-lus).—One 
of the most common galls on our oaks in the Northeastern 
