SECTION OF THE RIVER VOLKOF — LOWER BEDS. 
43 
bodies ornament the surface of the flagstone as at Tchudova. But besides one or 
two of the shells mentioned as occurring at that place, we here met with scales of 
fishes which characterize the Old Red system, — belonging to the genera Diplo- 
pterus and Glyptosteus (Ag.). 
If the sectional line be prolonged in the direction of Moscow, these lowest strata 
of the Devonian system pass beneath the red masses of Novogorod, Lake Ilmen 
and the Valdai Hills. But before we follow this ascending order, let us describe 
clearly the lower strata in the best natural section which the north ol Russia af- 
fords, and where, as before stated, they are seen in absolute contact with the 
uppermost Silurian rocks (see woodcuts, p. 28 and 30). 
Continuing the section on the Volkof, we find the uppermost Siluiian beds 
loaded, as explained, (p. 29) with Sphseronites, Favosites, and small Orthidce. 
These graduate upwards into flag-like courses more siliceous, which in ascending 
the river are overlaid by other thin-bedded strata, gradually becoming more led and 
green with marly way-boards. Concretionary forms begin to prevail, with courses 
of deep red and light green mottled marlstone, and at length red and green impure 
limestones, in beds from three to six inches, abound, interlaminated with much red 
marl. The fossils from about one verst south ot the village ol Bor to the hamlet 
of Vindin-Ostrof are unequivocally Devonian. 
Along the banks of the river at this place and at Prussino we collected the fol- 
lowing fossils: — Serpula omphalodes (Gold!.), Spirifer muralis (nob.), S. spcciosus 
(S. micropterus , V. Buch), S. Archiaci (Murch.), S. plicistria (D Arch, et De 
Vern.), Terebratula prisca (Schloth.), T. Meyenclorfii (named by us after our 
friend and companion Baron A \on Meyendorf), 1 ■ concentrica (V. Buch), T. 
ventilabrum (Phill.), Orthis striatula (Schloth.), LepUena productoides (Murch.), 
Productus spinosus (Sow.), according to M. V. Buch, Avicula Winthii (nob.), Mo 
diola antiqua (Goldf.), Belleroplion globatus (Murch.), B. armatus (nob.), Natica, &c. 
With these shells, among which are several species published as Devonian types 
from other parts of Europe, are also found fossil fishes, particularly scales of the 
Glyptosteus (Agassiz), a genus which also characterizes the Old Red Sandstone ot 
Scotland. 
The banks of this fine river diminish gradually from a height of sixty to 
seventy feet at Petropaulosk, to twelve and fourteen feet near Vmdin-Ostrof, 
Cherensorok, and Prussino, but the red marls and associated sandy calcareous 
flags and cornstones are traceable a little higher up the stream, and are then lost 
