208 
In addition to the preceding list of fossils, a specimen of 
Nautilus astacoides (Young and Bird) must be included as 
found in the Stephanoceras commune Beds. Also, the writers 
have to thank many members of the Society for working with 
such alacrity and spirit to collect in so short a time, at one 
visit only to the quarry, such a rich illustration, in quantity 
and kind, of the life of the periods of the Middle and Upper 
Divisions of our liassic deposits. The paleontological evidence 
of the fossils points to a great flux of geological time that must 
have elapsed between the close of the deposition of the Amal- 
theus spinatus Beds, followed by erosion to an enormous extent, 
and then to the deposition under new conditions of the dark 
grey clays above those beds, derived from the coal measures as 
before stated under the heading of Lithology. And with the 
new sediments, there followed modified forms of life, as is 
always the case. The subject is tempting to linger on, but 
passing from it to touch upon the visit to Gretton, and subse- 
quently to Ashton-under-Hill, we would call attention finally 
to these points:—(l) The line on the section parting the 
Ammonites Beds, namely, that of the Amaltheus spinatus, 
and that touching the base of the Stephanoceras commune 
Zone. This line marks clearly the great planes of erosion of 
the upper portion of the Middle Lias deposits. (2) Besides 
the physical changes that ushered in the re-appearance of an 
ancient brachiopod, viz., Lepteena (Dalman), which migrated 
from its Carboniferous home, and is so strangely met with in the 
Leptena Band of the Upper Lias (first discovered in Somerset- 
shire by a member of the Cotteswold Club, and afterwards in 
Gloucestershire by another member of the same Association), 
(3) We would not omit the considerations of physical geology, 
instanced in the formation of the singular course of geodes or 
of ovate concretions which, known as Fish Bed, or Insect Bed, 
is so constant in its occurrence, though not unique, for a similar 
course of concretions is found very constantly present in the 
Aegoceras Ibex Zone of our Middle Lias. One example at this 
moment is near the writer: it is an ovate concretion from the 
Ibex Zone, which contains a large and fine gastropod, Eucyclus 
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