204 
Proceedings of the Royal Society of Edinburgh. [Sess. 
The characteristic features of the fauna of the strata lying between 
the Hurlet Coal and the Hurlet Limestone, occurring on the horizon 
known as the Hurlet Alum Shale, supply the key to the position of the 
Hurlet datum line over the East and West of Scotland. It has already 
been shown that in the West of Scotland the shale lying immediately 
below the Hurlet Limestone contains a band principally made up of the 
two brachiopods Schizophoria resupinata and Productus semireticulatus. 
Below this comes another band of shale, consisting almost entirely of 
the remains of the four lamellibranchs Sanguinolites abdenensis, Streh- 
lopteria ornata, Actinopteria per sulcata, and Myalina verneuili. But 
an additional, and most remarkable, fact is that underlying the lamelli- 
branch band in the Campsie district occurs a bone bed which is identical 
in every respect with the Bone Bed underlying the first Abden Limestone 
on the Fife coast north of Kinghorn. Like it, this bone bed varies from 
1 to 2 inches in thickness, and is almost wholly composed of the scales, 
teeth, plates, spines, and bones of fishes, of which no two are in juxta- 
position. The following table gives the characteristic species of this 
important horizon as it has been traced in the various sections that have 
been described : — 
Howood. 
Glen Wynd. 
M'Culloch’s Slap. 
Baldow Glen. 
Boyd’s Burn. 
Burn Rannie. 
Glorat Mine. 
H 
5 
rG 
CD 
* 'p 
rH 
o 
O 
Thorn., Carluke. 
Addiewell Pit 16. 
Cobbinshaw. 
Tartraven. 
Rosyth Quarry. 
Charlestown Rly. Stn. 
First Abden Limestone. 
Coal Farm, St Monans. 
Bilston Burn. 
Catcraig, Dunbar. 
Telgngium affine L. & H. 
X 
X 
X 
X 
X 
X 
X 
Archceocidaris urei Flem. . 
X 
X 
X 
X 
X 
Serpulites carbonarius M‘Coy . 
X 
X 
X 
X 
Productus longispinus Sow. 
X 
X 
X 
X 
X 
,, semireticulatus Martin 
X 
X 
X 
X 
X 
X 
X 
X 
Lingula squamiformis Phill. 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Schizophoria resupinata Martin 
X 
X 
X 
X 
X 
Discina nitida Phill. 
X 
X 
X 
X 
Streblopteria ornata R. Eth., Jr. 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Sanguinolites abdenensis R. Eth., Jr. 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
,, costellatus M'Coy. 
X 
X 
X 
X 
X 
X 
Actinopteria per sulcata W" Coy . 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Myalina verneuili M‘ Coy . 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Posidonomya corrugata R. Eth., Jr. . 
X 
X 
X 
X 
X 
Belter ophon urei Flem. 
X 
X 
X 
X 
Orthoceras sp. . 
X 
>< 
X 
X 
Goniatite sp. 
The Hurlet Limestone does not present any outstanding palaeontological 
features by which it can be readily recognised. It is a crinoidal lime- 
