ON THE PILOBOLID.iE. 
135 
connected with the structure of the stem, which differs 
considerably in the two genera. 
In Pilobolus the stem is separated from the mycelium at 
its base by a transverse septum, and at its summit, just 
beneath the sporangium, it swells out into an ovoid or 
globular form, and, as we shall see presently, the sporange is 
violently projected when mature, sometimes to an enormous 
distance. The height of a species of Pilobolus rarely 
exceeds one inch, and is usually very considerably less. In 
the other genus the stem rises to a greater height, *in one 
species even to four inches, and remains slender and 
cylindrical throughout. When the sporange is mature the 
stem loses its stiffness, and, as it falls upon the substratum, 
the sporange is quietly deposited at a greater or less distance. 
Corresponding to this absence of projection of the sporange 
is the absence of the septum at the base and of the swelling 
at the summit of the stem. We may then subdivide the 
Pilobolidae as follows :— 
' Sporange violently projected. A swelling at tlie summit 
and a septum at the base of the stem .. Pilobolus. 
Sporange not projected. No swelling at the top of the 
k stem, no septum at the base . Pilaira. 
We will now proceed to consider the minute particulars 
of the structure and development of the genus Pilobolus and 
the many interesting questions connected therewith. The 
description is mainly founded upon my observations of 
Pilobolus Kleinii, but will apply, mutatis mutandis, to the 
other species. 
(To be continued.) 
GEOLOGICAL MAP OF NOTTINGHAM. 
We are glad to learn that the large Geological Map of the 
borough of Nottingham which was exhibited at the soiree held 
in connection with the visit of the Midland Union to Notting¬ 
ham in 1882 has now been published. It has been copied on 
the reduced scale of 3^- inches to a mile, or one-fourth the size 
of the original, and incorporated in Hr. Seaton’s report to 
the Town Council, on the “ Sanitary Condition of Nottingham 
in 1882.” The geological formations included within the 
limits of the borough boundaries are the Coal Measures, the 
Permian Lower Magnesian Limestone and Marl, the Lower 
Mottled Sandstone, Bunter Pebble Beds, Lower Keuper Base¬ 
ment Beds, “ Waterstones,” and Upper Keuper Marl of the 
New Bed, and the alluvial deposits of the Trent and the 
