P DICHAINA QUERCINA. 149 
Gall caused by ? Dicheena quercina, Fries. 
(Plates LXVII, LXVIILI.) 
Position of gall.—On the trunk of Quercus pedunculata, in 
Broomham Park, Guestling, Hastings. 
This enormous swelling affords an excellent illustra- 
tion of many such growths on oak, elm and other trees, 
in parks, groves, gardens, and woods in many 
localities. 
It is remarkable that these growths do not cause 
any noticeable diminution in the height, vigour in 
expansion, or scarcity of foliage of trees thus affected. 
Apparently the galls are not detrimental to the well- 
being of the trees. This, of course, is not unusual, 
because very few oak galls (excepting such as monopo- 
lise buds and catkins) interfere with the development of 
the surrounding tissues; a character more noticeable 
in the galls on, and in, leaves, than in any others. 
As far as can be ascertained, without cutting 
into this gall, it is composed of the same materials as 
the other portion of the trunk. It is without holes of 
any considerable depth, and appears to be perfectly 
solid. 
The bark, or cortex, is scabrous. Although very 
similar in appearance to'the bark of the trunk, it will 
not peel off in the same manner. 
The scale shown in each plate is 30 cm. (= almost 
12 in.) The dimensions are : 
Girth of trunk immediately beneath swelling 7 ft. 10 in. 
Distance from ground to top of swelling. . 6ft. 3in. 
Peripheral circumference of swelling . ‘ . 10ft. 3in. 
Girth of trunk and swelling at equatorial line 11 ft. 10 in. 
The fruiting stage of all the species of the genus 
Dichena is rarely seen. Of some species it is not 
known. Some species are common. All are true 
parasites. 
