tg21] WELLS—ZOOCECIDIA 369 
latter through the elimination of the bundles, but it may also 
have had an independent origin from the stock type; embryological 
evidence in this connection is not available. 
The pedicellate condition (19) constitutes the culmination of 
another line, in which all possible stages may be found in the oak 
cynipids. 
A special place has been given to those galls (20) which bear 
appendages on the gall body proper (larva containing region): 
It is believed these bracteate forms for the most part are derived 
from the non-bracteate forms. There are, however, such possible 
exceptions as the gall of Rhodites rosae L. or R. bicolor Harr., in 
which instances the appendages might be interpreted to be but the 
reappearance of certain normal parts. In so far as this is true 
they would be kataplasmic. 
In (21) is represented a type possessing highly elongated 
trichomes. All gradations from the smooth stock type (14) to 
extreme pubescence are known in the cynipid cecidial biota. 
It is better for the present to consider the free larval cell type 
(22) as an independent line, although, as already indicated, it may 
have been derived from the radiate-fiber form. 
A final line is that leading to the obliteration of the parenchy- 
matous cortical region (23), resulting in a firm, thin-walled structure. 
These galls are all very small. 
Before closing the account of the Cynipidae, mention should 
be made of the kataplasma shown in (24). Larva cells are organ- 
ized in the homogeneous tissue of the acorn. This may have 
arisen independently, or with greater probability it was derived 
through a change in point of attack on the part of insects forming 
a primitive leaf gall. 
Summary of phylogenetic data 
It will be. desirable to point out certain major evolutionary 
tendencies appearing in. widely separated groups which point 
toward an orthogenetic interpretation. (1) The tendency toward 
specific sclerenchymatization- in the formation of the lignified 
tissue forming the so-called protective layers-in the galls. This 
has appeared independently in Psyllidae, Itonididae, and Cynipidae; 
