16 4H. A. Howorth—Traces of a Great Post-Glacial Flood. 
water shell Cyrena fluminalis, now confined to the Nile and the southern 
latitudes of Asia, and in all probability also associated with the Mam- 
moths’ tusks which have been found in the estuary of the Humber, 
the Cyrena and the Mammoth being companions in the Thames 
Valley and elsewhere. Again, during the construction of the Forth 
and Clyde Canal, some beds were met with at Croftamie (Drymen 
Station). In a bed of blue clay the following shells were found: 
Cyprina islandica, Astarte compressa, Fusus antiquus, Littorina litorea, 
and Balanus, and in the same bed was a fragment of Deer’s horn 
114 inches long, which was declared by Professor Owen to be that 
of a young or female Reindeer of the existing species (Trans. Geol. 
Soc. of Glasgow, vol. v. p. 16). These shells, says Mr. Jack, indi- 
cate a climate not severe, though probably a little colder than the 
present climate of these latitudes. All the shells specifically dis- 
tinguished are living in the British seas (id. p. 25). This deposit 
was more than 100 feet above the sea-level. In other deposits near 
Loch Lomond, also described by Mr. Jack, and situated up to as high 
as from 120 to 262 feet above the sea-level, were beds of shells, 
which he describes as water-worn marine shells of species almost all 
now living in the British seas. The deposit, therefore, indicating a 
climate little more severe than our own (id.). 
In concluding this part of my argument, I would strengthen it by 
two quotations from the opinions of Sir Roderick Murchison, based on 
his continental experience. 
“But,” he says, “some of the very marine shells on which we 
have been insisting as proofs of the aqueous formation of this Boulder 
drift, are said to be Arctic species, and have therefore been quoted 
as indicating the prevalence of a colder climate in our latitudes in 
those days than at present. Hence, glaciers, it is supposed, may 
have been adjacent to such arctic animals. But what are the species 
of shells associated with the great Boulder driftin Denmark? Why, 
in many tracts, the very same which now live in the adjacent seas. 
And though several of the latter are Arctic species, no glaciers occur 
within several hundred miles of the sea in which they live. Again, 
the researches of Prof. E. Forbes in the Aigean and of Prof. Loven 
in the North Sea have taugh tus, that the more or less Arctic character 
of shells essentially depends upon the depth of the submarine zone 
at which the animals lived” (Russia and Ural Mountains, i. 551). 
Again, “ We were at one time disposed to think that the presence 
of sub-fossil shells of Arctic character naturally indicated the former 
presence of a much colder climate in those latitudes where they have 
been found; but, independent of discoveries in submarine life, we 
now hold that it is unnecessary to have recourse to such an argument, 
in relation to any phenomena in the British Isles or similar latitudes ; 
for we can easily imagine, that when very different physical features 
prevailed, and when lands now above the sea were beneath it, cold 
currents may have extended very far southward of the arctic circle, 
and have been inhabited by species now restricted (through geo- 
graphical changes) to a less horizontal range” (id. note 2). 
(To be continued.) 
