472 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 2, 



readily all traces of the external form of such vegetables would be- 

 come obliterated, and also how all distinct evidence from the state 

 of internal tissue should have disappeared. 



In Sweden, where the anthracitic or bituminous shale occurs 

 among the Silurians, it has been shown by Murchison* to rest upon 

 a sandstone containing Fucoidal remains, indicating the source from 

 whence the shales probably derived their carbonaceous matter. In 

 Russia, however, where they underlie limestones of the Llandeilo age, 

 they have less of an anthracitic, and more of a coaly nature ; since, 

 from the observations of Colonel Helmersen, these deposits contain 

 about 25 per cent, of bitumen, with a considerable amount of inflam- 

 mable gas. 



In the Silurians of the South of Scotland, vegetable remains are 

 apparently not confined to the anthracite-shales and their accom- 

 panying beds. There exists another zone in these Silurians affording 

 Fucoidal remains in at least one locality. This zone forms the beds 

 from whence Graptolites were first obtained by Prof. Nicol at Greiston 

 in Peeblesshire ; and, following these deposits from this locality 

 in the direction of their strike, W.S.W., we meet with them again at 

 Barlae, in the parish of Dairy, about seven miles north of the town of 

 New Galloway, in the Stewartry of Kirkcudbright. Here the Fucoid 

 remains occur under entirely different circumstances from those at 

 Glenkiln. They are in no way associated with anthracite- shales, 

 neither do they make their appearance in soft beds along with 

 Graptolites. 



The deposits in this locality consist of sandstones and flaggy beds : 

 the latter were formerly used for slating-purposes ; but, in conse- 

 quence of exfoliating by exposure to the weather, and requiring 

 heavy timber to support them, the working of these so-called slates 

 is now abandoned in the South of Scotland, the Welsh and Cumber- 

 land slates having supplied their place. On the faces both of these 

 sandstones and of the flaggy beds, various fossils are seen. Some- 

 times they occur in the form of the tracks of Annelids of the genus 

 Crossopodia, M'Coy ; and sometimes Nereites present themselves, 

 as well as the rare zoophyte Protovirgularia, M'Coy ; also filiform 

 bodies, the nature of which is somewhat uncertain, but having, in the 

 opinion of the late Prof. E. Forbes, some relation to the genus Old- 

 hamia of the Irish Cambrians ; and along with these, facoids of the 

 genera Palceochorda and Chondrites^ M*Coy, occur, the former in 

 considerable abundance. Of the branching fucoid. Chondrites^ 

 several species may be seen, and amongst these are C. informis^ 

 M'Coy, and C. acutangulus, M*Coy, fossils which are found in the 

 black slate of Skid daw. 



These fucoids present no traces of anthracite, but are converted 

 into the substance in which they lie ; and the physical evidence 

 associated with their occurrence leads to the inference that the strata 

 were formed m comparatively shallow water, since we have ripple- 

 marks on the faces of the beds ; these ripples, in some instances, 

 being partially filled with sand. 



* See Russia in Europe, vol. i. p. 15*, and Siluria, p. 318. 



