the whitened branches "clashed and clattered;" the "vile water rinnand o'erheid," and "routing as thonder," made "hideous trubil;" and to augment the uproar, the "griesly fisch," like the fish of eastern story, raised their heads amid the foam, and shrieked and yelled as they passed. "The grim monsters fordeafit the heiring with their sellouts;"--they were both fish and elves, and strangely noisy in the latter capacity; and the longer the poet listened, the more frightened he became. The description concludes, like a terrific dream, with his wanderings through the labyrinths of the dead forest, where all was dry and sapless above, and mud and marsh below, and with his exclamations of grief and terror at finding himself hopelessly lost in a scene of prodigies and evil spirits. And such was one of the wilder fancies in which a youthful Scottish poet of the days of Flodden indulged, ere taste had arisen to restrain and regulate invention. Shall I venture to say, that the ichthyolites of the Old Red Sandstone have sometimes reminded me of the "fisch of the laithlie flood?" They were hardly less curious. We find them surrounded, like these, by a wilderness of dead vegetation, and of rocks upcast from the sea; and there are the foot-prints of storm and tempest around and under them. True, they must have been less noisy. Like the "griesly fisch," however, they exhibit a strange union of opposite natures. One of their families--that of the _Cephalaspis_--seems almost to constitute a connecting link, says Agassiz, between fishes and crustaceans. They had, also, their families of sauroid, or reptile fishes--and their still more numerous families that unite the cartilaginous fishes to the osseous. And to these last the explorer of the Lower Old Red Sandstone finds himself mainly restricted. The links of the system are all connecting links, separated by untold ages from that which they connect; so that, in searching for their representatives amid the existences of the present time, we find but the gaps which they should have occupied. And it is essentially necessary from this circumstance, in acquainting one's self with their peculiarities, to examine, if I may so express myself, the sides of these gaps,--the existing links at both ends to which the broken links should have pieced,--in short, all those more striking peculiarities of the existing disparted families which we find united in the intermediate families that no longer exist. Without some such preparation, the inquirer would inevitably share the fate of the poetical dreamer of Dunkeld, by losing his way in a labyrinth. In passing, therefore, with this object from the extinct to the recent, I venture to solicit, for a few paragraphs, the attention of the reader.