10 HA. H. Howorth—Traces of a Great Post-Glacial Flood. 
But let us continue. We must remember that not only is the 
number of purely Arctic shells in these beds as compared with the 
whole number comparatively small, but that the fact of finding a 
few distinctly Arctic shells is balanced by the occurrence in certain 
of the beds of another class which tells an entirely different story, 
namely, shells characteristic of a more southern latitude than our 
own, southern forms which occur beside these Arctic forms. 
In the thirtieth volume of the Journal of the Geological Society, 
Mr. Mellard Reade describes the marine shells from the Lancashire 
drifts in the neighbourhood of Liverpool and Warrington. In this 
paper, pp. 84 and 35, he says, “ Though all, with the exception of 
Astarte borealis, Leda pernula, and Saxicava norvegica (which are of 
course northern shells), may be described as Irish sea shells, yet, 
if we make a fair comparison, we shall find that the Boulder-clay 
assemblage possesses a more northern facies than the present fauna 
of the British Seas.” Notwithstanding this sentence, Mr. Reade 
very frankly points to the presence of Venus Chione, Dentalium 
tarentinum and Cardium tuberculatum, as distinctly southern shells, 
aud adds, The presence of Venus Chione in the low level Boulder-clays 
as well as in the Macclesfield drift, where it was first discovered by 
Mr. Darbishire, is certainly a remarkable fact ; but it is not an isolated 
one; for Cardium aculeatum and Cardium pygmeum, both Lusitanian 
forms, are found in the Scotch drift, and in the Irish drift southern 
forms also occur,” adding in a note, ‘“ Forbes notes the discovery by 
Captain James of Turritella incrassata, a Crag fossil, a southern 
form of Fusus, and a Mitra allied to the Spanish species in the 
Wexford gravels.” 
In a paper by Mr. Darbishire, on the Shell-drift at Leyland, 
which was published in the same volume of the Geological Journal, 
the author says, “The list, although containing a few names of 
species of a northern character (Astarte and Fusus), contains also 
several shells of markedly southern origin. Venus (Cytherea) 
Chione, which has been identified at Macclesfield, and in several 
of Mr. Reade’s Liverpool localities, may almost be called a 
characteristic fossil at Leyland. Cardium tuberculatum (rusticum, 
F. and H.) occurs not unfrequently. One perfect and characteristic 
hinge of Mactra glauca (helvacea, F. and H.) was found. All 
these are essentially southern species. The only shell which is 
peculiarly Arctic in character is Fusus (Trophon) craticulatus, Fabr., 
a species now living in Greenland, of which one fine and (for 
drift) fairly fresh-looking shell has been found. The same species 
was identified at Moel Tryfaen” (op. cit. p. 89). The presence of 
these southern forms is surely just as eloquent and just as forcible 
evidence as that of the northern species, and when these two papers 
were discussed, Mr. G. Jeffreys said, ‘‘ All the shells found in these 
Lancashire beds were just such as might have been thrown up on 
the shore, though the matrix in which some of them are found is 
not sandy. . . . He did not regard any of the shells as truly Arctic, 
and doubted whether any of them afforded clear evidence of climate.” 
Mr. Prestwich said, “In the overlying Boulder-clay the fragments 
