TRANSACTIONS OF THE SECTIONS. 95> 
rocks and limestones containing Lower Silurian fossils, or that the last are suc- 
ceeded by micaceous schists and flagstones often passing into a younger gneiss. 
The second part of the communication related to the Old Red Sandstone, properly 
so defined, as exhibited on the east coast, between the Orkney and Shetland Islands 
on the north, and Banffshire and Morayshire on the south, various points of which 
the author visited last summer. In Caithness and the Orkney Islands, accompanied 
by Mr. Peach, the author made various interesting additions to his former knowledge, 
and profited by the researches of Mr. Robert Dick of Thurso. His belief was sus- 
tained that the ichthyolitic flagstones of Caithness and the Orkneys, with their 
numerous fossil fishes, constitute the central member of the Old Red series, the lower 
part of which is made up of powerful conglomerates and a very great thickness of 
thin-bedded red sandstone, the whole being composed of the detritus of the more 
ancient crystalline rocks. The central flagstones are surmounted by other sandstones, 
rarely red, and usually of yellow colour, which occupy the promontories of Hoy Head, 
Dunnet Head, &c. 
The chief additional data which had been gained by Sir Roderick during his last 
visit were owing, in the first instance, to a discovery by Mr. Martin of Elgin, of a 
large bone in the same beds at Lossie Mouth, which had formerly afforded large 
scales of the supposed fish, called Staganolepis by Agassiz. On visiting these quar- 
ries with the Rev. G. Gordon, he was so fortunate as to discover other portions of 
this large animal; so that comparative anatomists may determine whether it be, as 
the author believed, really reptilian. The existence of reptiles during the forma- 
tion of this deposit is, indeed, established beyond a doubt; since many slabs have 
long been found in the coast quarries of Cummingston, in which are the footprints of 
both large and small reptiles, each footprint having the impression of four or five 
claws to it. A slab, transmitted by Capt. Brickenden, is in the Geological Society’s 
Museum, and others have recently been sent to the Museum of Practical Geo- 
logy, London, as contributions from Mr. P. Duff of Elgin, and other persons. The 
presence of large reptiles, as well as of the little Telerpeton, in a deposit which all 
geologists have hitherto considered to be an upper member of the Old Red Sandstone, 
is therefore established. 
After noting certain fossil fishes which occur in parts of the Duke of Richmond’s 
estates in Banffshire, the author proceeded to review the relations of the great masses 
of sedimentary deposit lying along the eastern and southern faces of the crystalline 
rocks of the Grampians, which have been hitherto classed as pertaining to the Old 
Red Sandstone, though he does not pretend as yet to be competent to describe their 
detailed features. On these points, however, which Mr. D. Page is working out with 
ability, he begs to offer the following suggestion. The true base of the-Old Red 
Sandstone, properly so called, is seen in Shropshire and Herefordshire to be a red 
rock, containing Cephalaspis and Pteraspis, which gradually passes down into the 
grey Ludlow rock; and in both of these contiguous and united strata, remains of large 
Pterygoti, but of different species in the two bands, are found. Now, although the 
_ Arbroath paving-stone, and the grey rocks ranging to the north of Dundee, litholo- 
gically much resemble the uppermost Ludlow rock, they contain the Cephalaspis 
Lyellit as well as Pterygoti, and must, under every circumstance, be viewed as the 
base of the Devonian rocks. In speaking of the lowest member of the Old Red Sand- 
stone, as characterized by the Cephalaspis, the author expressed his conviction, that 
in the north-eastern Highlands and Caithness that zone is represented as above men- 
tioned, by the vast thickness of thin-bedded red sandstone and conglomerates, which 
underlies the bituminous flags of Caithness. 
The author, who had recently visited Dura Den, in Fifeshire, in the company of 
Lord Kinnaird and the Rey. Dr. J. Anderson, whose work, ‘ The Course of Creation,’ 
is well known to geologists, declared that there could be no doubt that the yellow 
sandstones, that tract in Fife which pertains truly to the Old Red group, are entirely 
subjacent to the lowest carboniferous sandstones, and are probably of the same age as 
the upper yellow sandstones of Elgin. A drawing, prepared by Lady Kinnaird (the 
splendid specimen having been placed in the museum at Rossie Priory), of the fossil 
fish Holoptychius*, nearly three feet in length, which was found on the occasion of 
this visit on the property of Mrs. Dalgleish, was exhibited; and as this form abounds ; 
* This large species has proved to be the H. Andersoni, Ag. 
