246 
Massee . — The Structure and 
that shadow in the origin of the Discomycetes, through various morpho- 
logical and physiological changes in the ascophore, the asci also undergo 
important changes, resulting in the formation of a cylindrical ascus, contain- 
ing eight spores of equal size, arranged in a single row, as in the genera 
Stephensia , Genea , &c. Such an ascus closely resembles those met with in 
the genus Peziza , only lacking the well-known arrangement for suddenly 
ejecting the mature spores into the air, by the process known as c puffing 
In the Tuberaceae, as in all primitive groups of Fungi, when the 
advantages arising from dispersion by wind had not been realized, the 
spores are of exceptional size, and usually with a greater or less amount of 
ornamentation of the epispore. The object of this ornamentation is obscure, 
possibly its function is protective, while the spores are subjected to various 
mechanical processes in the stomach of some rodent. The ornamentation 
may take the form of raised ribs, anastomosing to form a more or less 
regular network ; of coarse warts or tubercles ; or of long spines or finger- 
like processes. The wall of the spore is in all instances relatively very 
thick, and of a soft or gelatinous consistency, and is in all cases perfectly 
smooth and even until approaching maturity, when the ornamentation, 
of whatever nature, is always due to skrinkage of special portions of the 
wall, and to the bulging out of other portions to form the ribs, warts, &c. 
If mature spores are treated with a five per cent, solution of potassic 
hydrate for some time, the ornamentation of the wall disappears, and 
it becomes smooth and even. In those genera leading up to the Disco- 
mycetes, the spores are smaller, and smooth or nearly so. 
Geographical Distribution. 
Owing to the subterranean habit, members of the Tuberaceae are almost 
invariably passed over by travellers, and even in Europe the group has not 
appealed to mycologists generally ; some half-dozen, amongst whom may 
be mentioned, Berkeley and Broome in England, Vittadini in Italy, Tulasne 
in France, and Hesse in Germany, having furnished the bulk of information 
we possess at the present day. Harkness has done some valuable pioneer 
work in the same direction in California, and Rodway has discovered some 
very interesting species in Tasmania. Duthie has also met with certain 
edible species in India. On the whole it may be said that the family 
is cosmopolitan in its distribution. 
Numerically the family is quite a small one, we have in Britain 
11 genera and 32 species. The total number of known genera is 27, 
including 140 species. 
The following table gives the known distribution of genera and species 
throughout the world, and clearly indicates that our knowledge of the 
number of species recorded for a given continent, is in proportion to the 
