The most considerable collection of the Lower Old Red fucoids which I have yet seen is that of the Rev. Charles Clouston of Sandwick, in Orkney,—a skilful cultivator of geological science, who has specially directed his palæontological inquiries on the vegetable remains of the flagstones of his district, as the department in which most remained to be done; but his numerous specimens only serve to show what a poverty-stricken flora that of the ocean of the Lower Old Red Sandstone must have been. I could detect among them but two species of plants;—the one an imperfectly preserved vegetable, more nearly resembling a club-moss than aught else which I have seen, but which bore on its surface, instead of the well-marked scales of the _Lycopodiaceæ_, irregular rows of tubercles, that, when elongated in the profile, as sometimes happens, might be mistaken for minute, ill-defined leaves; the other, a smooth-stemmed fucoid, existing on the stone in most cases as a mere film, in which, however, thickly-set longitudinal fibres are occasionally traceable, and which may be always distinguished from the other by its sharp-edged outline, and from the circumstance that its stems continue to retain the same diameter for considerable distances, after throwing off at acute angles numerous branches nearly as bulky as themselves. In a Thurso specimen, about two feet in length, which I owe to the kindness of Mr. Dick, there are stems continuous throughout, that, though they ramify in that space into from six to eight branches, are nearly as thick atop as at bottom. They are the remains, in all probability, of a long, flexible weed, that may have somewhat resembled those fucoids of the intertropical seas, which, streaming slantwise in the tide, rise not unfrequently to the surface in from fifteen to twenty fathoms of water; and as, notwithstanding their obscurity, they are among the most perfect specimens of their class yet found, and contrast with the stately araucarians of the Coal Measures, in a style which cannot fail to delight the heart of every assertor of the development hypothesis, I present them to the reader from Mr. Dick’s specimen, in a figure (fig. 54) which, however slight its interest, has at least the merit of being true. The stone exhibits specimens of the two species of Mr. Clouston’s collection,—the sharp-edged, finely-striated weed, _a_, and that roughened by tubercles, _b_; which, besides the distinctive character manifested on its surface, differs from the other in rapidly losing breath with every branch which it throws off, and, in consequence, runs soon to a point. The cut on the opposite page (fig. 55) represents not inadequately the cortical peculiarities of the two species when best preserved. The surface of the tubercled one will perhaps remind the Algologist of the knobbed surface of the thong or receptacle of _Himanthalia lorea_, a recent fucoid, common on the western coast of Scotland, but rare on the east. An Orkney specimen