1 6 Massee.- — A Monograph of 
The genera Bovista and Lycoperdon are very closely related, 
the only point of difference being that in the latter there is 
a sterile porous, basal stratum, which may be considered as a 
sterile portion of the gleba, and in some species is continued 
downwards as a more or less elongated stem-like base. In 
Bovista there is no sterile basal stratum, hence the species 
are invariably sessile. Intermediate stages connect the two 
genera, which might with advantage be united into one. In 
Geaster the peridium is more highly differentiated, and is 
described as follows by De Bary 1 : 4 G. hygrometricus is up 
to the period of perfect maturity a roundish body, which may 
be of the size of a hazel-nut, and remains beneath the surface 
of the ground. Six layers may be distinguished in the peri- 
dium in a vertical longitudinal section a short time before 
the compound sporophore is mature. The outermost layer is 
of a brownish colour, flaky and fibrous, and is continued on 
one side into the mycelial strands which spread through the 
soil, and on the other passes into the second layer ; a thick 
stout brown membrane entirely covering the compound sporo- 
phore. This is followed towards the inside by a white layer, 
which is more largely developed at the base of the compound 
sporophore than elsewhere, and is immediately continuous at 
that spot with the inner peridium and the gleba. Both of 
these last-mentioned layers are formed of stout closely-woven 
hyphae running in the direction of the surface, and may be 
combined under the name of the fibrillose layer The inner 
of the two is lined on the inside by the collenchyma-layer, 
except where its basal portion passes into the gleba. This 
layer is cartilaginously gelatinous and consists of hyphal 
branches of uniform height connected together without inter- 
stices, which are placed palisade-like vertically to the surface 
and are bent as they spring from the hyphae of the fibrillose 
layer. The strongly thickened stratified walls of the cells of 
this layer have great capacity for swelling. Inwards from the 
collenchyma is a white layer, the innermost region of which is 
1. c. p. 316. 
