. The testimony of the rocks; . frond which I haveplaced beside it bears the impress of a character scarce lossequivocal. The flora of the Oolite was peculiarly a floraof intermediate forms. We recognize another characteristic of our Oolitic florain its simj^le-leaved fronds, in some of the species not alittle resembling those of the recent Scolopendrium, orIlarts-Tongue fern, — a form regarded by Adolphe Brog-niart as peculiarly characteristic of his third period ofvegetation. These simple ferns are, in the Helmsdale de-posits, of three distinct types. .There is first a lanceolateleaf, from t
. The testimony of the rocks; . frond which I haveplaced beside it bears the impress of a character scarce lossequivocal. The flora of the Oolite was peculiarly a floraof intermediate forms. We recognize another characteristic of our Oolitic florain its simj^le-leaved fronds, in some of the species not alittle resembling those of the recent Scolopendrium, orIlarts-Tongue fern, — a form regarded by Adolphe Brog-niart as peculiarly characteristic of his third period ofvegetation. These simple ferns are, in the Helmsdale de-posits, of three distinct types. .There is first a lanceolateleaf, from tw^o and a half to three inches in length, ofnot unfrequent occurrence, which may have formed, how-ever, only one of the four leaflets, united by their pseudo-footstalks, which compose the frond of Glossopteris, — adistinctive Oolitic genus. There is next a simple ovate lan-41* 486 ON THE LESS KNOWN ceolate leaf, from four to five and a half inches in length,which in form and venation, and all save its thrice greater Fig. size, not a little resembles the leaflets of a Coal Measureneuropteris, — iV. acuminata. And, in the third place,there are the simple leaves tliat in general outline resem-ble, as I have said, the fronds of the recent Ilarts-Tonguefern i^Scolopendriimi vulgare)^ except that their base is lan-ceolate, not cordate. Of these last there are two kinds in FOSSIL FLORAS OF SCOTLAND. 487 the beds, representative of two several species, or, as theirdifference in general aspect and detail is very great, may-hap two several genera. The smaller of the two has aslender midrib, depressed on its upper side, and flanked oneach side by a row of minute, slightly elongated protuber-ances, but elevated on the under side, and flanked by rowsof small but well marked grooves, that curve outwards tothe edges of the leaf. The larger resemble a Taeniopterisof the EngUsh and Continental Oolites, save that its midribis more massive, its venation less at right angles with thestem
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