No. 7.] DAWSON — SCOTTISH DEVONIAN PLANTS. 387 



The remarkable plants from the Skiddaw slates described by 

 Nicholson as Buthotrephis HarJcnessi and B, radlata * have 

 also been examined by me, as well as some additional specimens 

 from the same formation collected by Dr. G. M. Dawson. 

 Nicholson says of the latter species : — " If its vegetable nature 

 be conceded, it can hardly be referred to the Algae." It seems 

 not unlikely, as Nicholson indeed suggests, that both plants may 

 belong to the same species, and that this had the habit of growth 

 of Annularia and resembled A. laxa of the American Devonian. 

 If a land plant, it is probably the oldest at present certainly 

 known. f 



With these plants, Prof. Nicholson sent a fibrous body from 

 the Upper Llandeilo of Hart Fell, near Moffat, which at first 

 sight had the appearance of a fragment of coarse-grained wood. 

 On microscopic examination of it, however, I concluded that it 

 had been a bundle of spicules of a sponge of the type of Hyalo- 

 netna. This I still believe to be its true nature. 



In studying the plants of the older rocks, the botanist requires 

 to be on his guard as to the Algae and Zoophytes of these forma- 

 tions which simulate land plants. In the latter group I know 

 no forms more deceptive than those of Hall's genus Inocaulis, 

 which is regarded as a relative of the Graptolites. A specimen 

 now before me, from the collection of Col. Grant, of Hamilton, 

 Ontario, in its ramification and appearance of foliage, bears the 

 closest resemblance to a lycopodiaceous plant, and I have seen 

 what appears to be the base of a Dictyonema from the Niagara 

 formation, which might readily be mistaken for a small and 

 peculiar species of Psilophyton. 



Messrs. Jack and TCtheridge have given an excellent summary 

 of our present knowledge of the Devonian Flora of Scotland, in 

 the Journal of the London Geological Society. From this it 

 would appear that species referable to the genera Calamites, 

 Lepidodendron, Lycopodites, Psilophyton, Arthrostigma, Archce- 

 ppteris, Caulopteris, Palwopitys, Araucarioxylon, and Stigma- 

 ria have been recognized. 



* Geological Magazine, Vol. VI. 



f Since the above was written, Lesquereux has described supposed 

 land plants from the Cincinnati Group (Lower Silurian) of Ohio. 

 Saporta has discovered what he regards as a fern in rocks of similar 

 age in France, and Claypole will shortly describe an apparently 

 lepidodendroid tree (Glypiodendron) from the Clinton Group of Ohio ; 

 but neither of these is quite so old as the Skiddaw plants. 



