[It were well, in dealing with the very ancient floras, in which equivocal forms occur that might have belonged to either the land or the sea, to keep in view those curious plants of the present time, the habitats of which are decidedly marine, but which are marked by many of the peculiarities of the seed-bearing plants of the land. The superiority of Zostera to the common sea weeds of our coasts appears to have struck in the north of Scotland eyes very little practised in such matters, and seems to have given rise, in consequence, to a popular myth. _Zostera marina_ abounds on a series of sand banks, partially uncovered by the larger stream tides, which lie directly opposite the town of Cromarty, near the spot pointed out by tradition as the site of an earlier town, which was swept away some two or three hundred years ago by the encroachments of the sea. And these banks, with their thick covering of green Zostera, used to be pointed out by the fishermen of the place, in my younger days, as the _meadows_ of the old town, still bearing their original coverings of vegetation,--a vegetation altered no doubt by the "sea change" that had come over it, but still essentially the same, it was said, as that which had smiled around the old burgh, and not at all akin to the brown kelp or tangle that every storm from the boisterous north-east heaps along the shore. It was virtually affirmed that the luxuriant terrestrial grasses of ancient Cromarty had made a virtue of necessity in their altered circumstances; and that, settling down into grasses of the sea, they remained to testify that an ancient Cromarty there had _once been_. _Zostera marina_, like most plants of the land, ripens its seeds towards the close of autumn; and I have seen a smart night's frost at this season, when coincident with a stream tide that laid bare the beds, nip its seed-bearing stems by thousands; and have found them strewed along the beach a few days after, with all their grass-like spikes fully developed, and their grain-like seeds charged with a farinaceous substance, which one would scarce expect to find developed in the sea. In the higher reaches of the Cromarty Firth, the Zostera beds, which are of great extent, are much frequented, during the more protracted frosts of a severe winter, by wild geese and swans, that dig up and feed upon the saccharine roots of the plant. The Zostera of the warmer latitudes attain to a larger size than those of our Scottish seas. "A southern species," says Loudon, "_Zostera oceanica_, has leaves a foot long and an inch broad. It is used as a thatch, which is said to last a century; bleaches white with exposure; and furnishes the rush-like material from which the envelops of Italian liquor flasks are prepared." The simple rectilinear venation of ribbon-like fronds, usually much broken, that occurs in the Lower Old Red Sandstone, has often reminded me of that exhibited by this exotic species of Zostera.] [Illustration: Fig. 118. FUCOID.]