1868. | of Norway and Scotland. 463 
the period between the commencement of the severe climate and the 
deposition of the shell-clays. 
Another period also may be noted, between the beginning of 
life within the waters and the point of its extremest abundance. 
In such localities as the Upper and Lower Foss near Christiania, 
the lower part of the shell clay is very finely laminated, and 
contains comparatively few fossils. 
The fine laminations of the lower clay, also, are characteristic 
of the beds at Paisley and throughout the whole Firth of Clyde,— 
beds equally deficient in fossils. A few foram‘nifera of the hardiest 
types are the only animals which have yet been detected in the 
laminated mud of the Clyde district. The flowing of mud-laden 
waters from inland ice would produce precisely such a mud as that 
we have observed beneath the more abundantly fossiliferous clays 
of Norway and Scotland. The highly comminuted particles depo- 
sited in layers would cause the laminations, while the coldness of 
the waters would limit the development of animal life. 
A period of most abundant arctic life succeeded that of which 
we have in the laminated mud so imperfect a record. We have a 
deep sea instead of the estuaries into which the cold waters of great 
rivers were poured. The profuseness of molluscan life at this 
period, both in Norway and Scotland, is most remarkable. The 
beds of Pecten Islandicus, e. g., extend along the Firth of Clyde at 
intervals for many miles. ‘The shells in the clay-pits at Paisley 
interfere with the working of the clay. Exactly as at the present 
day, molluscan life is abundant at the edges of the glaciers as they 
overhang into the sea, so it must have been during this part of the 
glacial epoch. Another arctic characteristic is the connection of this 
abundance of life with the extensive development of a few species, 
rather than the distribution of the fauna into many genera. 
The shell-beds of Scotland indicate a degree of cold almost as 
great as that manifested by the most arctic shell-clays of Norway. 
There is a remarkable correspondence between a clay at Moss 
on the south of the Christiania fjord and a clay at Errol in the Carse 
of Gowrie. The characteristic shell in both clays is Leda arctica. 
It evidently has not been drifted but occurs in situ. Leda arctica is 
found living on the east coast of North America and within the 
arctic circle, not in the British seas or North Pacific. 
At Moss and Errol, also, we find that the shells with which 
Leda arctica is associated are precisely the same and equally arctic in 
their characteristics. Tellina calcarea is large and abundant, while 
Buccinum Groenlandicum may also be collected. It is not there- 
fore the question of an isolated species; and the Norwegian and 
Scotch beds at these localities must be held to represent the same 
climate, so far as similarity of climate can be represented by 
correspondence of fauna. 
VOL. V. 2k 
