1903] BRIEFER ARTICLES 225 
mal growth kept pace with the larvae, which are comparatively large for 
so small a mushroom. The hole traced out in fig. g appears to repre- 
sent the habit of the larva. It has been suggested that most gall insects 
produce hollow or chambered abnormal growths, and that this may not 
be a form which habitually produces galls. It is of course possible 
that the eggs were laid very early and that this stimulus produced a 
gall, whereas had they been laid later the mushroom would have been 
destroyed in the ordinary way. The argument that this is a true gall 
insect would be the size of the gall, and of the larva producing it 
(5-6™™" at least). Larvae as large as these could not work in the ordi- 
nary Omphalia pileus because the flesh is too thin and would not offer 
sufficient food and protection, which is always sought by the insect in 
laying eggs. It is at least interesting to find such a gall in a group of 
plants where such a growth has not been reported in our literature. 
This note, perhaps will bring similar cases to light —CHakLES THOM, 
Cornell University, Ithaca, N. Y. 
SELECTED NOTES. II.—LIVERWORTS. 
DumortigRA.—- Although the genus Dumortiera has as a whole 
become greatly reduced in the structure of its gametophyte from the 
typical Marchantia form, and has, generally, hardly a trace left of the 
complex chambers and nutritive outgrowths characteristic of the group, 
there are certain species which show, normally or occasionally, enough 
resemblance to the typical form to leave no doubt that its simplicity 
is secondary, acquired through retrogressive development from more 
complex members of the Marchantiaceae. Of the several species of 
Dumortiera there is only one in which traces of dorsal chambers have 
been described. This is D. irrigua L., which was studied by Leitgeb’ 
from herbarium material only. At the growing point on the upper 
surface he finds and figures quite distinct chambers, without, however, 
a very definite mouth opening. ‘he upper covering of the chambers 
becomes broken and disappears more and more on the older part of 
the thallus, until finally only the basal parts of the chamber walls 
are left as reticulations on the surface. Leitgeb also mentions “ ktrze- 
ren oder langeren Haarpapillen” which occasionally arise from the 
Surface of the thallus and represent the cell rows which fill the air- 
chambers of Marchantia. Campbell (JJosses and Ferns) finds no trace 
of any such complexities on the thallus of D. ¢richocephala from the 
* Untersuchungen iiber die Lebermoose, Heft 6, 1881. 
