er very much from those held formerly by most
geologists; and even at present there are, as I have mentioned before, a
few upholders of those older views.

The sea, I think, must have gradually crept across England from the east
during, or shortly after, the Forest-Bed period, so as to separate the
south from the north, whilst Ireland and Scotland were then still
connected with one another. At a later stage, the sea also partially
invaded Ireland, and this condition is very roughly represented on the
accompanying map. Mr. Kendall kindly drew my attention to the fact that
several notable areas on which shelly drift has been observed are here
placed upon the land; but it must be remembered that one stage only can
be shown on the map, and that the sea covered more ground a little
later. Many of the smaller islands in the glacial sea, too, are not
shown. The map, in fact, is merely meant to give a general idea of the
manner in which the great northern sea moved westward and slowly covered
a large portion of the British Islands. These peculiar geographical
conditions explain, I think, better than anything, the absence from
parts of the Midlands and the north of England of such a number of
terrestrial invertebrates which are otherwise widely distributed over
the British Islands. In spite of the fact that a large portion of the
British Islands became submerged, we possessed at that time an extensive
area which has since been claimed by the sea, so that there was ample
room for the present fauna to survive the Glacial period. The climate
during this period was probably much the same as it is at present,
though moister, with cooler summers and milder winters.

[Illustration: Fig. 6.--Map of the British Islands, showing
approximately in what manner the sea may have invaded the country from
the east during, or shortly after, the Forest-Bed period. The darkly
shaded parts indicate the areas covered by water, and the lightly shaded
and white portions what was land at that time.]

It may be asked what proof we have of such an extensive submergence of
England and Ireland. My own views are principally based on the general
distribution of the fauna in the British Islands, and the belief that
nothing but a mild climate during the Glacial period could have brought
it about. On purely geological grounds, however, some geologists,
notably Mr. Mellard Reade, have come to a similar conclusion. "The whole
of Lancashire and Cheshire," he rema