also fartlier characterized by having their spherules not enclosed
in filiform tubes, as in the true Sphæria, (vid. sup. T. 6.
under Sphæria spernwides). This genus, which comprehends
many species, unites Circinostoma and Exormatostoma of Mi-
G r a y , which, in his Natural Arrangement, have the following
characters ;
CiKciNosTOMA. Thollus 0 . Thecre grommg under the epidermis
o f plants, and perforating it, placed in a circle ; mouths close
together.
E x o u m a to s to m a . Thallus 0. Thecæ growing under the epidermis
ofplants, and perforating it, scattered; mouths upright.
These genera run much into each other ; yet, if the species
of the former had been more constant to their character, the
latter might have been retained. But in so natural a group as
the Sphærideæ, an ill-defined genus is a serious evil. I have,
therefore, for the present at least, proposed the one above mentioned
as comprising a natural assemblage of plants, and, I trust,
calculated to render the study less confused.
Fig. 1. Leaves o f Pinus picea with Cryptosphoeria Taxi, nat. size. Fig. 2.
A leaf magnified. Fig. 3. A section o f a spherule; and, Fig, 4. Spondes,
as seen separating from the hardened gelatinous mass when moistened,— both
highly magnified.