H. H. Howorth—Traces of a Great Post-Glacial Flood. 18 
Lough 57 species of shells have been found in the drift clays by 
Messrs. Bryce and Hyndman. Of these, only two, Leda oblonga and 
Trophon clathratum, are not now found in the British seas, but only 
in the seas further north (Grou. Mac. Vol. X. p. 449). 
Mr. Bell has also shown that a bank of shells, now submerged, 
off the mouth of Belfast Lough, and known as the urbot Bank, 
consists largely of drift shells. Speaking of these latter shells he 
says, ‘Amongst the species, all of which are small, intermixed with 
Celtic and southern forms, are nine or ten whose congeners now live 
in the northern seas,” adding, “'The intermixture of southern forms 
with those of higher latitudes does not interfere with the placing of 
these beds in the Post-Tertiary Series, since they are equally present 
in the Killiney drifts, the Lancashire drifts, and in some of the 
Scottish Clyde beds, especially the one near Greenock. Indeed, 
amongst a parcel of minute shells and shelly clay from the latter 
place, I detected the fry or extreme young of some living Mediter- 
ranean forms, Conus Mediterraneus and Cardita trapezia” (id. p. 450). 
Let us now go beyond our own land. “At Lillehersstehagen, which 
lies about an English mile east of Uddevalla, an extensive deposit of 
shells is partially exposed. Here the upper layer gives a singular 
result. Mixed with the universal Trophon clathratus (which is a 
high northern species, and found living only within the Arctic 
circle), are many shells of rather a southern type, such as Ostrea 
edulis, Tapes pullastra, Corbula gibba, and Aporrhais pes-pelicani. 
Ail these species, however, have been recorded by Sars as inhabiting 
the coast of Finmark, although they are also natives of the Mediter- 
ranean. According to Dr. Torell, a living oyster has never been 
found in the seas of North Greenland and Spitzbergen” (Jeffreys’ 
Report on Upper Tertiary fossils of Sweden, Brit. Assoc. Report, 
1863, 1874, and 1875). This is paralleled in Norway, where southern 
forms of shells have occurred mixed with Northern ones in the 
raised beaches. 
No doubt both in Norway and Sweden we find raised beds of 
shells showing different climatic conditions, some presenting a more 
Arctic facies than others, but all of them prove the existence of 
open water and not of ice-bound coasts when they were deposited ; 
but the difference of the contents of the beds may have its lessons 
exaggerated. “It is true that in some districts the Post-Tertiary fauna 
differs from that of another, at no great distance, in its apparently 
more northerly or southerly aspects, which unquestionably might 
arise from local causes, independently of climatal changes.’ The 
same thing holds good at the present time. For instance, Fusus 
Turtont, Fusus Norvegicus, Fusus Berniciensis, and Saxicava (Panopea) 
Norvegica, all northern species, have been taken living on the coasts 
of Durham and Northumberland, while no trace of them has been 
found on the western coasts of Scotland. We may reasonably infer 
that similar variations occurred in the seas of ancient times, yet no 
one would ascribe them to change of climate ” (Robertson, Notes on 
Raised Beach at Cumbrae, Trans. Geol. Soc. of Glasgow, vol. v. p. 193). 
Messrs. Crosskey and Robertson most aptly say: ‘A species may 
