290

GEOLOGICAL EVIDENCES

of the Tertiary beds; but we have not yet succeeded in de-tecting among them a single dicotyledonous tree of the highersub-classes, and only a few dicotyledonous leaves. They areall coniferous gymnospermse, chiefly of the pine and arauca-rian families; and in the Fauna associated with them, wefind that the prevailing forms are reptilian. The reptile oc-cupied as large a place in these Secondary periods as thatoccupied by the mammal in the Tertiary ones. So far, in-deed, as we yet definitely know, there existed during theseherpetological ages only two species of mammals,—a smallmarsupial and small insectivorous animal. Again, in theFlora of the Paleeozoic division, we still find the pine and thearaucarian, mixed, however, with extraordinary vegetabletypes, some of which have become wholly obsolete, and someof which are linked by but faint analogies to aught that now•exists; but which, generally speaking, seem to be, thoughligh representatives of their kind, of a kind in itself not high.In the Fauna of the period, down till at least the base of themiddle Paleeozoic system, fishes seem the dominant forms,—fishes, many of them of great size, formidably armed, anduniting in their organization, reptilian to the ordinary ichthyicpeculiarities, but in not a few of their number destitute ofan internal skeleton of bone. True, during these ages thereptile also existed, but in such scanty proportions, that whilethe Coal Measures have yielded their ichthyic remains bythousands and tens of thousands, they have yielded to the se-dulous search of the geologist only three reptiles and the traceof a fourth; and while in single platforms of the Old RedSandstone there are perhaps as many fishes entombed as areat present living on all the fishing banks of the country, theentire system has furnished the remains of but one reptile(if, indeed, the lacertian of Spynie in reality belong to it), andthe foot-tracks of a few others. In the Lower Palseozoic for-mations, the trace of even the fish becomes unfrequent, and