236 Geological Society :— 
Loch Fyne to Jura Sound) the grits and slates are intimately mixed, 
with numerous intercalated beds of greenstone, some being of great 
thickness. Mr. Jamieson pointed out that this feature of the di- 
strict has hitherto in great part been misunderstood, and that Mac- 
culloch was in error when he denominated these rocks ‘ chlorite- 
schist.” 
The probable relationship of the rocks of the Islands of Shuna, 
Luing, and Scarba to those of Jura and Bute were then dwelt upon; 
the greenstones of Knapdale, &c., and their relation to the sedi- 
mentary rocks, were described in detail; and the limestones of 
the district briefly noticed. As no fossils have hitherto been found, 
paleontological evidence of the age of these rocks is wanting; but 
the author, regarding their general resemblance to the quartz-rocks, 
limestones, and mica-schists of Sutherlandshire, thinks them to be of 
the same date as those rocks of the North-west Highlands. 
2. “On the position of the beds of the Old Red Sandstone in 
the Counties of Forfar and Kincardine, Scotland.” By the Rev. 
Hugh Mitchell. Communicated by the Secretary. ; 
In Forfar- and Kincardine-shire, south of the Grampians, the Old 
Red Sandstone is developed in the following series, with local modi- 
fications :—I1st (at top), Conglomerate; 2nd, grey flagstone with 
intercalated sandstone (about 40 feet thick at Cauterland Den, 
120 feet at Carmylie) ; 3rd, gritty ferruginous sandstone, with 
occasional thin layers of purplish flagstone. Of the last, 120 feet 
are seen at Cauterland Den; it occurs also at Ferry Den, &c. The 
flagstone of this third or lowest member of the group yields Ripple- 
marks, Rain-prints, Worm-markings, and Crustacean tracks (of 
several kinds, large and small). Parka decipiens has been found in 
the lowest grits; and Cephalaspis in the sandstone at Brechin, im- 
mediately under the grey flagstones. 
In the second member, namely the grey flags, Fish-remains have 
of late been found more or less abundantly throughout the district, 
together with Crustacean fossils. Cephalaspis Lyellit, Ichthyodoru- 
lites, Acanthodian fishes, Pterygotus, Eurypterus, Kampecaris For- 
fariensis, Stylonurus Powriensis, Parka decipiens, and vegetable re- 
mains are the most characteristic fossils. 
The author pointed out that some few genera of Fish and Crus- 
taceans were present both in this zone and in the Upper Silurian 
formation, and that still fewer links existed to connect the fauna of 
the Forfarshire flags with the Old Red Sandstone north of the Gram- 
pians, with which it appears to have, in this respect, almost as little 
relation as with the Carboniferous system. With the Old Red of | 
Herefordshire these flags appear to have some few fossils in common ; 
but of about twenty species found in Forfarshire, only about four 
could be quoted from Herefordshire. 
In conclusion, the author noticed the vast vertical development of 
the whole series, and its great geographical extent ; and particularly 
dwelt upon the distinctness of the fauna of the flagstones of Forfar- 
shire, as giving good grounds for the treatment of the Old Red 
Fauna as peculiar to a separate geological period, both as distinct 
