1858.] MUECHISON NOETHERN HIGHIAITDS, ETC. 415 



intermediate zone is wanting in Russia*, the lowest Devonian or 

 Old Red stage being there absent. 



In Russia the lowest Devonian stage consists of the sandstones 

 and shales which contain the fossil fishes of the north of Livonia, and 

 those of the environs of Dorpat and of Tellin on the Lake of Rus- 

 tuck. The fishes of this zone are those which Asmus first described 

 (including the great Aster olepis), and of which Pander has in the 

 last year given a more detailed and extensive account, and with that 

 genus we now also have there the well-known Coccosteus of the north 

 of Scotland. These beds graduate upwards into dolomitic limestone 

 and shale richly charged with Mollusca, which in Germany, France, 

 and elsewhere are recognized as middle and upper Devonian types, — 

 the most frequent beiag Spirifer Archiaci, Sp. Anosqffl, Productus 

 prodiLctoides, Terehratula lAvonica, and abundance of Encrinites, 

 <fec. Now, in the very same beds with these sea-shells, corals, and 

 crinoids, we find the Holoptychius Nohilissimus, and many of those 

 fishes which are characteristic of the central and upper portions of 

 the Old Red Sandstone of Perthshire in Scotland ; in short, fragments 

 of such ichthyolites are often found in hand-specimens, intimately 

 mixed up with the above-mentioned mollusks, and in localities widely 

 separated from each other, in several Governments of Russia. By 

 this intermixture, it is demonstrated, that the theory, partially in- 

 dulged in, of the freshwater origin of the Old Red ichthyolites is 

 quite untenable. The uppermost Devonian stage of Russia, whether 

 composed of red or whitish soft sandstone, or of greenish marls, as 

 on the Priutchka River ia the Yaldai Hills, where I have examined 

 it, and where it underlies conformably everything carboniferous, is 

 laden with remains of ichthyolites, three of which are also identical 

 in species with the fossil fishes of the Old Red Sandstone of Scotland 

 and different from any known in the Carboniferous series. These 

 are the Holoptychius Nohilissimus, Glyptosteus favosus, and Diplo- 

 ])terus macrocephaliLS. Judging, therefore, from the organic remains 

 alone, we see that the lowest British zone, or that with Cephalaspis 

 and Pteraspis, Pterygotus, and Parlca decipiens, is wanting in Russia. 

 There, the inferior strata, or those containing Coccosteus, Dipterus, 

 Asterolepis, &c., represent the Caithness or central zone of our 

 country ; whilst the superior Russian members are equivalents of 

 the higher portions of the Old Red Sandstone of Scotland and the 

 limestones and slates of Devonshire, since they unite the fishes of 

 the former country with the sea-shells of the latter. A reference to 

 the work, ' Russia and the IJral Mountains,' and to the ^ Fishes of 

 the Old Red Sandstone' of Agassiz, suffices indeed to establish the 

 correctness of this view, now that we know what is the real strati- 

 graphical base of the British Old Red Sandstone ; for all the species 

 mentioned in other publications as common to Britain and Russia 

 (to the number of twenty- one) occur in the middle and upper 

 strata only of the Old Red of our own country f. 



* See ' Snuria,' new edition, p. 384, 



t Tables accompanying the following memoir will show the comparison 

 VOL. XV. PAET I. 2 H 



