HIGHEST BEDS OF THE DURHAM COAL MEASURES. 221 
about thirty years before, from some forgotten locality on the 
south bank of the Wear, west of Hylton. It had subsequently 
been examined by Professor Phillips, who referred, or was dis- 
posed to refer, the shells to a species of Ancylus, or river limpet. 
No further notice appears to have been taken of the discovery 
for several years, though the previous existence of this genus in 
the coal measures—or even in any formation older than Tertiary 
—had not been recorded. 
Until the spring of 1863, Mr. Vint’s specimen remained the 
only one of this interesting fossil; the lost locality not having 
turned up, either in the memory of Mr. Vint, or by independent 
discovery. But one day last spring, while examining the 
northern bank of the Wear, opposite to Claxheugh, about two 
miles west of Sunderland, I came upon a band of ironstone, 
associated with shale, which contained Mr. Vint’s Ancylus in 
great quantities; and in the shale underlying the ironstone I 
also found the same fossil somewhat differently preserved, and 
not in such numbers as in the ironstone itself. 
A rather hasty study of the materials thus acquired led me to 
conclude that the fossil was not an Ancylus, but an Hstheria, and 
hence an Entomostracan. But Professor T. Rupert Jones to 
whom I submitted some of my specimens, differs from my 
opinion. Both he and Mr. T. Davidson, in fact, are persuaded 
that the fossil in question is a Brachiopod of the genus Discina. 
Which of these opinions is the true one, I scarcely feel competent 
to say. But whether the fossil be an Ancylus, a Discina, or an 
Estheria, its occurrence is of interest in Carboniferous palaeon- 
tology; and instead of prematurely attempting to determine its 
true relations, let me rather give some particulars of its character 
and mode of occurrence. 
About two miles west of Sunderland a fault crosses the Wear 
in a northerly direction, and brings up the Coal Measures into 
sections where there otherwise would have been only the rocks of 
the Permian series. The former strata may be seen on each bank 
of the river; but their exposure is best seen on the north bank, 
where a series of impure sandstones intercalated with light grey, 
arenaceous shales with fossils belonging to Neuropteris and Cala- 
