60 Geological Society. Mr. Murchison's 



which the authors had previously obtained of the relation and con- 

 tents of the old red or Devonian series. The central districts of 

 Courland have been, for the first time, proved to contain rocks of 

 this age charged with typical fossils, both fishes and shells. A sec- 

 tion of the Diina river above Riga which exhibits some undulations 

 of the strata, exposes siliceous limestones, subordinate to red and 

 greenish shale ; whilst the country between Riga and Dorpat is oc- 

 cupied by sands and marls. M. Pander, who now resides in this 

 district, has collected a large and instructive series of its organic 

 remains, chiefly from the banks of the river Aa ; and among the 

 Ichthyolites which they obtained from him, the authors recognised 

 remains of Coccosteus and Holoptychius similar to those previously 

 collected by them in the Waldai" Hills, and which Professor Agassiz 

 has identified specifically with forms described by him from the old 

 red sandstone of Scotland. Professor Owen has also identified 

 among teeth from the eollection of M. Pander, two or more varie- 

 ties of the genus Dendrodus (Owen), equally characteristic of the 

 old red sandstone of Scotland, one of them being indeed undistin- 

 guishable from the Dendrodus of that author, described from spe- 

 cimens found at Scat's Craig near Elgin. 



In the marls and sands of Dorpat, Professor Asmus of the Uni- 

 versity at that place has collected and is describing certain gigantic 

 bones, which were formerly supposed to belong to Saurians, but 

 which, by their analogy to existing skeletons, he has shown to belong 

 to fishes*. A single bone of one of these remains is nearly three feet 

 long, and according to the estimate of Professor Asmus, the Ich- 

 thyolite of which it is a part must have had, when entire, a length of 

 not less than thirty-six feet. The union of these fishes, some of the 

 species of which, as above stated, are typical of the old red sand- 

 stone of the British Isles, with numerous fossil shells which have 

 been found to characterize the beds of the Devonian age in 

 England, Belgium, and the Boulonnais (an union was pointed 

 out last year as resulting from an examination of the provinces of 

 St. Petersburgh, Novogorod, Olonetz, &c), is now more amply con- 

 firmed by reference to the structure of the north-western govern- 

 ments of Russia, through which the same system is spread. 



Southern Zone of Devonian Rocks, or Geological Axis of Russia in 

 Europe. — Previous to their visit to the central and southern regions 

 of Russia, the authors believed, in common with their precursors, 

 that the ascending order of the strata was continuous from the Bal- 

 tic provinces on the north to the Black Sea and Sea of Azof on the 

 south, with the exception only of the granitic rocks and carboni- 

 ferous tracts of the southern steppes. They were undeceived, 

 however, by discovering in the heart of Russia (Orel, Voroneje, 

 &c.) a great domelike elevation, which is composed of rocks 



* At the request of Mr. Murchison, Professor Asmus has prepared and 

 sent to England duplicate casts of these the most remarkable and most gi- 

 gantic fossil fishes ever yet discovered. One set of these has been given by 

 Mr. Murchison to the British Museum, another to the Geological Society 

 of London, and a third to Professor Agassiz. 



