234 Massee.—A Monograph of the Geoglosseae. 
Affinities. 
The constant characteristics of primitive types of Fungi in 
the various families of both Ascomycetes and Basidiomycetes 
are (i) comparative absence of differentiation of the sporophore, 
and (2) large coloured spores, the latter being often also multi- 
septate and the epispore more or less ornamented. The genus 
Geoglossum possesses these features in a very pronounced 
form ; the ascophore is a simple, erect, more or less club- 
shaped structure, the upper portion of which is fertile, the 
thinner basal portion sterile, and called the stem. In G. hir- 
sutum , the simplest form known, the transition from the 
sterile to the fertile portion is not indicated externally ; in 
the other species there is a very slight ridge at the com- 
mencement of the ascigerous portion. The spores in all the 
species are large, brown, and multicellular ; but there is 
a gradual decrease in the size of the spores and in the 
number of component cells from G. hirsutum , where the 
spores are almost as long as the ascus, and consist of fourteen 
cells, to the G. glutinosum group, in which the spores are 
shorter, and generally four-celled. In all the species of 
Geoglossum every part of the plant is black externally. 
Following directly we have the genus Mitrula , the black 
species of which are externally quite indistinguishable from 
the species of Geoglossum , but are supposed to be generically 
distinct on account of the somewhat shorter, hyaline spores, 
which in the simplest forms are often four-celled, and in the 
highest forms have become very small and one-celled. In 
Mitrula the terminal ascigerous portion becomes more sharply 
defined from the stem, and is also often brightly coloured, 
every portion being covered by the hymenium. The next 
genus in the sequence of evolution is Leotia , which agrees 
with Mitrula so far as the spores are concerned, but differs 
in the form of the ascigerous portion, which is more or less 
pileate, or shaped like the cap of an Agaric, the margin 
curving inwards towards the stem. If we imagine the hollow, 
erect, fertile portion in Mitrula (Figs. 54, 59, 60) pressed down 
