Vol. 58.] JURASSIC OF THE SOUTH WALES DIRECT LINE. 729 
Paleontological Notes. 
Rhynchonella calcicosta._-This seems to differ but very slightly 
from the typical form which occurs so abundantly in the Angulatus- 
and Lower Bucklandi-Beds of Keynsham (near Bristol); it is, 
however, more flattened. 
Pseudodiadema (?)—The small echinid-spines are here placed 
under this genus, because they exactly resemble the spines found on 
the same horizon at New Clifton, where they are associated with 
portions of the test. 
Til. THe Sopsury Tunnet. 
This tunnel extends for a distance of about 23 miles, from Old 
Sodbury to near Acton Turville. Starting on the west in the 
Jamesoni-Shales of the Lias, it emerges on the east through the 
massive limestones of the Great Oolite, piercing in its course every 
intermediate horizon. 
Our knowledge of the beds through which the tunnel passes has 
been chiefly obtained from a careful examination of the material 
that has been brought up, partly from the boring of the shafts 
themselves, but mainly from the boring of the tunnel. A few 
surface-exposures have aided in confirming some of our conclusions. 
We have also derived very valuable assistance from the specimens 
collected at the surface, when the shafts were in course of construction. 
The specimens are labelled with the approximate depth, in each 
shaft, at which rocks of that particular kind were encountered. 
By the kindness of the engineer (Mr. Grierson) and the agent 
(Mr. Manton) we have been afforded every facility for examining 
these specimens, as well as for studying the geological section 
constructed from them by the late engineer to the section 
(Mr. Katzenstein). 
The exact determination of the vertical succession has, however, 
been a matter of very considerable difficulty. 
In the first place, since rocks of almost identical character recur 
again and again at very different horizons, it becomes impossible to 
assign a block, found on the tips and containing definite fossils, . 
to its correct horizon, unless the labelled specimens of identical 
nature contain fossils. The fossils themselves have consequently 
to be employed to determine the vertical succession, by assuming the 
same zonal sequence as in neighbouring districts. The value of the 
work is, in such cases, reduced to the mere registration of the 
occurrence of particular species in a particular kind of rock. 
In the second place, rocks of well-marked |ithological character, 
and common on the tips, contain no fossils and cannot be matched 
by any of the rock-specimens preserved from the shaft-borings ; 
their position is therefore entirely problematical, and can only be 
assumed to be the same as that of similar rocks from other districts. 
We shall consequently, in all cases of doubt, state the data on which 
our surmises are founded. 
