197 
1916-17.] The Hurlet Sequence and the Abden Fauna. 
hesitation in regarding it as the equivalent in the east of the Blackbyre 
Limestone of the west. 
A comparison of that part of the section which lies between the White 
Coral Limestone, No. 3, and the Productus giganteus Limestone,' No. 7, shows 
a most remarkable and interesting difference both in the thickness and 
general succession of the strata as developed at the opposite extremities 
of the syncline, though the distance between the two sections is less than a 
mile. This is shown in fig. 3. 
The shale a in the section near Coal Farm lies immediately below the 
Coral Limestone, and has a striking resemblance to the fossiliferous shale 
lying below the Blackbyre Limestone of the West of Scotland. The 
similarity of the White Coral Limestone to the Blackbyre Limestone has 
already been noted, as it presents exactly the same stratigraphical, physical, 
and paleontological features as that limestone in the West of Scotland, 
the shale / in the section having yielded an exactly similar fauna to that 
which characterises the Hurlet Alum Shale horizon of the West of Scot- 
land. The lamellibranch and the brachiopod bands are well marked, and 
the Bone Bed is represented by scales and fragments of fish remains, though 
they are not so abundant as at some of the other localities. The section 
at the west side of the syncline at St Monans Burn presents a number of 
striking differences from that seen at the Coal Farm end, showing that 
at the latter locality, land and estuarine conditions must have prevailed, 
whereas in the former more or less continuous sedimentation took place. 
The evidence afforded by these two sections, and the light which they 
throw upon the physical conditions which supervened upon the deposition 
of the Blackbyre Limestone all over the Midland Valley, is of exceeding 
great interest, but these details cannot be discussed here. The succeeding 
limestones in this section have been correlated with those of the West of 
Scotland, as indicated by the lettering in the table and in the series of 
comparative vertical sections given at the end. The palaeontological 
evidence in support of these correlations will be given in the succeeding 
part of this paper. 
IX. The Bilston Burn Section. 
We recross to the south side of the Firth for the purpose of examining 
the sections exposed in the Bilston Burn and on the shore at Aberlady 
Bay and Dunbar. We shall see that the section at the first of these 
localities presents a strong resemblance to that seen between Kinghorn 
and Kirkcaldy, while those seen at the second and third localities approach 
more closely to that just described at St Monans. 
) 
