Dr. Nicholson — On Plants in the Skiddaw Slates. 495 



entertained of the vegetable nature of some even of tlie most ancient 

 of these. Many, however, as believed by Professor E. Forbes and 

 Mr. Salter, are certainly referable to the tracks or burrows of marine 

 animals. More recently the Cambrian rocks of Sweden have yielded 

 to the researches of Torell and Linnarsson some remarkable im- 

 pressions and casts of fossils, which are believed to be of a vege- 

 table nature (Gteol. Mag., September, Vol. VI., p. 393, Plates XL, 

 XII., and XIII.). In Britain there is not, as far as I am aware, any 

 instance of the occurrence of plant-remains in deposits of Lower 

 Silurian age, as to the nature of which all authorities are agreed.' 

 The Oldhamia of the Cambrian rocks is believed by Mr. Salter to be 

 a plant, but good authorities would place it either amongst the 

 Polyzoa or Hydrozoa. The Cruziana semiplicata of the Lingula Flags 

 has often been assigned to the Fucoids, but it is believed by Mr. Salter 

 to be " the filled-up burrow of a marine worm" (Mem. Geol. Survey, 

 vol. iii., p. 248). Long ago Professor McCoy described from the Skid- 

 daw slates (lowest Llandeilo) certain fossils which he believed to be 

 fucoids (Quart. Journ. Geol. Soc, vol. iv., p. 223, and Pal. Foss., 

 pi. i. a). After studying a large number of specimens, however, I 

 have been compelled to come to the conclusion, held by Mr. Salter 

 and Professor Harkness, that these fossils (viz. PalceocJiorda major, 

 P. minor, and Chondrites acutangulus) are truly referable to the 

 action of marine worms. Within the last few years, however, I 

 have obtained from the Skiddaw Slates several fossils, which certainly 

 do not admit of being explained in this manner, though I would not 

 go so far as to assert that they are unquestionably plants. The age 

 of the deposit in which they occur renders them, at any rate — what- 

 ever their true nature may be — of sufficient interest to merit a short 

 description. 



Buthotrephis MdrTcnessii, n. sp. (PI. XVIIL, Fig. a). In his Palaeon- 

 tolog}' of New York, Professor Hall describes several species of plants 

 under the generic name Buthotrephis, their range in time extending 

 from the Calciferous Sandstone up to the Clinton Group (Upper 

 Silurian). The characters assigned to the genus are as follows: — 

 " Stems sub-cylindric or compressed, branched ; branches numerous, 

 divaricating, leaf-like ; structure vesicular" ? (See Pal. N. York, 

 vol. i., p. 8.) The nature of the fossils described under this head is 

 such as to show clearly that, if not of vegetable origin, the}'' are 

 certainly not referable to the operations of Annelides, Molluscs, or 

 any other animals. This is proved by the fact that they are always 

 more or less regularly branched ; and also by their not being simple 

 impressions on the sediment, but by their possessing, on the other 

 hand, a true organic structure, differing in colour and grain from 

 the surrounding matrix, and sometimes even exhibiting a carbona- 

 ceous texture. 



In the upper beds of the Skiddaw Slates, I have found specimens 

 of a fossil apparently belonging to the genus Buthotrcjjhis, and bearing 

 considerable resemblance to B. gracilis, more especially to the variety 



1 "With the details of Mr. Ilicks's recent discovery of plants in the Cambrian 

 Rocks of St, David's I am not acquainted. 



