8 
SHEPPARD : INTER-GLACIAL GRAVELS OF HOLDERNESS. 
great beach and other deposits along the coast then which may have 
modified the estuary), and in its estuary the Cyrena would flourish 
among some marine shells as the genus flourished in Eocene times in 
the south of England among oysters and other marine species. Now 
bring in the ice with its entangled marine shells, mingle the whole 
together, and you have the Kelsey Hill Gravels as the washings. It 
is worth bearing in mind that there is evidence that, at some period 
before the ice invasion, the country stood higher than at present and 
therefore the mouths of rivers would stand further seaward." 
" Now as to the value of the shell as evidence of climate. The 
oft-cited case of Cyrena fluminalis has long been regarded as one of 
the most conclusive proofs of a warm inter-glacial period in Holder- 
ness, as in other parts of England. You will find, in all text books 
the statement that the species occurs in the Nile, the implication 
being sometimes explicitly stated that it is found nowhere else. 
Were this actually the case the shell would, I think, undoubtedly 
furnish evidence hard to controvert of the prevalence of a warm 
climate in Britain at the time when Cyrena fluminalis was an inhabi- 
tant of our rivers. It has, however, long been known to conchologists 
that the species lives in the rivers of Sicily, a fact of great significance, 
as many of the Sicilian streams are fed by melting snow, and are 
therefore, at certain times of the year, but little above freezing point, 
A yet more important extension of the known range of the shell 
however has been brought under my notice by Mr. J. W. Taylor, of 
Leeds. He says : — ' It would seem to be a general inhabitant of 
' N.E. Africa and Central and Western Asia ; these latter are on the 
' authority of Professor von Martens, one of our very best concholo- 
' gists. (Samarcand and the River Oxus are two places mentioned).' " 
" We have here a series of facts which in my judgment quite 
dispose of Cyrena fluminalis as evidence of an inter-glacial period or 
of warm condition. Though it is the custom to regard the arid 
deserts of Turkestan as regions of torrid heat, it must not be forgotten 
that they experience winters of great severity, and an examination 
of the " Challenger " charts shows that the January isotherm of 
30 ''F. passes a little to the northward of Samarcand, which, therefore, 
has a winter similar in severity of cold to that of Cape Farewell, the 
