220 P. Macnair § J. Reid — Palceontological Considerations — 



Land plants of the same genera and species are met with in the 

 Old Eed Sandstone and Devonian of Europe and North America. 

 In littoral deposits they occur abundantly, but in deep-water deposits 

 they are more sparingly met with. On the other hand, traces of 

 seaweeds undoubtedly occur in the Old Red Sandstone. In the 

 sandstones of Gaspe, Nematophyton (with which Pachytheca is 

 closely associated) is prevalent. This plant has been referred by 

 Penhallow and Carruthers to the Alga?. Paclujtlieca is met with in 

 the sandstones of Murthly 1 and in the flags of Forfarshire, while in 

 a late edition of Page's Geology an undoubted fucoid is figured from 

 the Old Eed Sandstone of Roxburghshire. Nicholson also says : 

 " The Old Red Sandstone of Scotland contains a good many frag- 

 ments supposed to belong to seaweeds." 2 



The Key to the Devonian Question. 



Perhaps in the Middle Devonian of the Russian formation we find 

 the strongest evidence in favour of the marine origin of the Old Red 

 Sandstone. From the northern to the southern boundary of Russia 

 the Devonian deposits have remained comparatively undisturbed to 

 the present day. In the Russian formation " the Devonian and Old 

 Red Sandstone types appear to be united, the limestones and marine 

 organisms of the one being in terstra titled with the fish-bearing sand- 

 stones and shales of the other." 3 " Indeed, cases occur where in the 

 same band of rock Devonian shells and Old Red Sandstone fishes lie 

 commingled." i The lower division of the Devonian being absent 

 in the Russian formation, no crustaceans or cephalaspidiau fishes 

 occur; but in the lower part of the system (Middle Devonian) we 

 find the remains of the genera of Osteolepis, Dipteriis, etc., " which 

 are specifically identical with those of the Old Red Sandstone 

 of Scotland." 5 The characteristic Holoptychius nobilissimus and 

 Boihriolepis and other fishes of the Old Red Sandstone of Scotland 

 are met with in the upper division of the Russian Devonian, as well 

 as in the Devonian of North America. In the fish-bearing sand- 

 stones of the Devonian of Russia no marine shells occur. This may 

 be generally said of the red sandstones and shales of the Old Red 

 Sandstone of Britain, though in the Welsh area Conalaria (whose 

 recent representative is a denizen of the deep sea) is met with. 

 Orthoceras dimidiatum and other marine remains occur in the Old 

 Red Sandstone of Lanarkshire. It is in the St. Lawrence basin, 

 however, where marine shells are more numerously met with. Sir 

 Wm. Dawson says of the marine shells of the Nova Scotian beds : 

 " With respect to the fossils, I may remark that they are all marine ; 

 that they belong to numerous genera and species." 6 " Some of the 

 fine beds (of Gaspe) hold shells of Lingnla and ITodiomorpha of 



1 See Nature, 10th April, 1890. 



2 "Manual of Paleontology," 1872, p. 521 ; also Annals of Botany, vol. v, 

 No. xviii, p. 158. 



3 "Textbook of Geology," A. Geikie, 1SS2, p. 703. 



4 Ibid., p. 704. 



5 Ibid., p. 704. 



6 " Acadian Geology," 1S55, p. 315. 





