126 Reports and Proceedings — 



that the crystalline rocks of the Outer Hebrides formed the western 

 limit of the ( Cambrian area of deposition, and that the basin was in 

 the form of an inland lake. 



On the otlier hand, looking at the fossil evidence both of the Irish 

 and Welsh Cambrian beds, he was of opinion that the beds of this 

 basin were in the main, if not altogether, of marine origin, and that 

 the basin itself had a greatly wider range eastward and southward, — 

 the old Archaean ridge of the British Isles forming but a small por- 

 tion of the original margin. 



3. " The Devonian-Silurian Formation." By Prof. E. Hull, LL.D., 

 F.E.S., F.G.S. 



The beds which the author proposed to group under the above 

 designation are found at various parts of the British Isles, and to a 

 slight extent on the Continent. The formation is, however, eminently 

 British, and occurs under various local names, of which the follow- 

 ing are the principal : — 



England and Wales. 



Devonshire. — The Foreland Grits and Slates lying below the 

 Lower Devonian beds ("Lynton Beds"). 



Welsh Borders. — "The passage-beds" of Murchison, above the 

 Upper Ludlow Bone-bed. and including the Downton Sandstone, and 

 rocks of the ridge of the Trichrug. These beds form the connecting 

 link between the Estuarine Devonian beds of Hereford (generally, 

 but erroneously, called the "Old Eed Sandstone") and the Upper 

 Silurian Series. 



South-east of England (Sub-Cretaceous district). — The author as- 

 sumed, from the borings at Ware, Turnford, and Tottenham Court 

 Eoad described by Mr. Etheridge, that the Devono-Silnrian beds lie 

 concealed between Tottenham Court on the south and Hertford and 

 Turnford on the north. 



Ireland. 



South.— "The Dingle Beds," or '^ Glengariff Grits and Slates," 

 lying conformably on the Upper Silurian Beds, as seen in the coast 

 of the Dingle pi'omontory and overlain unconformably by either Old 

 Bed Sandstone or Lower Carboniferous beds, 10,000 to 20,000 feet. 



North. — " The Fintona Beds," occupying large tracts of London- 

 derry, Monaghan, and Tyrone, resting unconformably on the Lower 

 Silurian beds of Pomeroy, and overlain unconformably on the Old 

 Eed Sandstone or Lower Carboniferous beds, 5000 to 6000 feet in 

 thickness. 



Scotland. 



Beds of the so-called " Lower Old Eed Sandstone," with fish and 

 crustaceans, included in Professor Geikie's " Lake Orcadie, Lake 

 Caledonia, and Lake Cheviot," underlying unconformably the Old 

 Eed Sandstone and Lower Calciferous Sandstone, and resting uncon- 

 formably on older crystalline rocks. Thickness in Caithness about 

 16,000 feet. 



The author considered that all these beds were representative of 

 one another in time, deposited under Lacustrine or Estuarine con- 

 ditions, and, as their name indicated, forming a great group inter- 



