Page:The Geologist, volume 5.djvu/42

3828 [sic] Carboniferous forms, ten Silurian, eight common to Silurian and Carboniferous, and ninety-seven—slightly more than half—peculiar to Devonshire. At present (confining ourselves also to South Devon) the catalogue gives a total of two hundred and twenty-six, of which thirty-four are Carboniferous, six Silurian, and a hundred and eighty-six peculiar to the district; or putting the totals at each period = 1000, and equating the other numbers to this, the figures stand as in the following table, and show a decided advance Devonian-ward.

Doubtless the fact that the Carboniferous forms so greatly outnumber the Silurian has a meaning. Does not this greater organic affinity betoken a closer connection with the more modern than with the more ancient period? Is it not an intimation that the lowest beds of Devonshire do not constitute the basement of the Devonian system?—that the county has an ample development of Upper and Middle, but not of Lower Devonian rocks?

Hitherto we have accepted the opinion of Professor Sedgwick respecting the Petherwin and Barnstaple beds; namely, that they are strictly contemporary, and constitute the uppermost division of the Devonian system. It may, perhaps, be well, before closing this paper, to go somewhat fully into the arithmetic of the question.

A glance at Table IX. will show the number of fossil species and genera found in the two areas.