496 Dr. Nicholson — On Plants in the Skiddaw Slates. 



crassa, described by Hall from tbe Clinton Group (Op. cit. vol. ii., 

 pi. V. fig. 3). The characters, however, of these fossils are so little 

 definite, and the above-mentioned species is so variable, that I have 

 not thought it safe to include our specimens under it, more especially 

 as they exhibit some curious points which are not present in the 

 American form. The fossil in question shows unequivocal organic 

 structure, consisting of dark, nearly black, cylindrical, regularly 

 branching stems, usually about a line in width, which can not be 

 obtained in relief, as they split right through when the shale is laid 

 open. The best specimen which I have found is broken, and con- 

 sists of a central stem giving off alternately on both sides long 

 secondary branches, which diverge at angles of from 25° to 60°. 

 The terminations of none of these branches are shown, though one 

 attains a length of nearly three inches ; nor is any diminution in 

 their diameter observable. The secondary branches in turn bear, at 

 irregular intervals, on both sides, short tertiary offsets, which taper 

 rapidly to a point, and would seem, therefore, to be of the nature of 

 leaves, rather than the bases of fresh branches, though it is not 

 possible to be quite certain of this. 



This singular fossil is unquestionably the remains of some organism, 

 and cannot be referred to the action of marine animals of any kind. 

 Its regular mode of branching demonstrates this beyond a doubt. 

 The proofs of its being a vegetable, though less strong, are, I think, 

 sufficiently weighty, more especially as it is difficult to see what else 

 it could possibly be. If it were a Sponge, a Polyzoon, or a Ccelen- 

 terate of any kind, it would almost infallibly exhibit some structure 

 by which this could be certainly determined, the nature of the sedi- 

 ment being such that the most delicate details — as shewn by the 

 accompanying Graptolites — would be preserved. It is not, however, 

 siliceous, chitinous, or calcareous, and it is merely of a much coarser 

 grain than the enveloping matrix. As to its place in the vegetable 

 kingdom, it were premature, in the absence of perfect specimens, to 

 offer any decided conjecture, though the mode of branching would 

 not lead us to refer it to the Alg^. Hall, however, thinks that 

 ButhotrepMs is "doubtless allied to the recent Fucus," and it 

 certainly presents some resemblance to the " fucoids" of the lower 

 Ludlow Eock of the neighbourhood of Ludlow. 



Loc. — Upper beds of the Skiddaw Slates, Thornship Beck, near 

 Shap. 



ButhotrepTiis (?) radiata, n. sp. (PL XYIII. Fig. B.). — This fossil 

 occurs only in conjunction with the preceding, and in exactly the same 

 state of preservation, so that there is some reason to think that they 

 are different portions of the same organism. From the contiguity of 

 the two in some specimens — though this, of course, may be accidental 

 — I have been led to think it possible that this form may in reality 

 be the whorled leaves of B. Harhiessii, but I have never seen them 

 in direct connection. Its description, however, as a distinct species 

 must be regarded as simply provisional, and I have placed it in the 

 genus ButhotreiMs only in view of its probably being a fragment of 

 another form. 



