28 
UNGULITE GRIT OF ST. PETERSBURG!!. 
calcareous, frequently concretionary, of a harder consistency, and apparently of a 
very durable composition. This is well seen in the escarpments on the banks of 
the river Narva, on which the ancient Moscovite castle stands, where a ferruginous 
and calcareous cement has so bound together the minute and broken Ungulites 
with coarse grains of sand, that the faces of the rock are quite impervious to the 
action of the weather. For a long time we supposed that the Ungulites were ex- 
clusively found in the lower sandstone or grit, but at Vassilkova on the river Lava 
(between the Volkof and the Siass), M. Pander has found them intermixed with 
the Orthidse, Orthoceratites, Trilobites and Sphseronites of the overlying pleta 
limestone ; the calcareous mass in which these remains occur being superposed 
to a considerable thickness of Ungulite sandstone. 
With the exception of two very rare species of Orbicula 1 which we detected on 
the banks of the Tosna and the brook near Crasnoe-celo, the Ungulites seem to be 
the sole tenants ot this sandstone. These fossils, to which we naturally paid great 
devotion, as being the most venerable animal remains of northern Europe, are not 
confined to one part of the rock, but are scattered throughout it, usually in vast 
quantities, often in very small fragments, but at intervals are better preserved. 
On the Volkof and Siass the same courses of clay or shale are observed as at the 
Tosna, and the sand-rock is often of a delicate pink colour, but with the exception 
of some irregular courses of sub-concretionary purple grits, the whole mass falls 
readily to pieces under the hammer. The Ungulites vary in their dimensions from 
the size of a pea to that of a sixpence 2 , and occur in great profusion. We refer to 
our description of these singular protozoic fossils in the second volume, merely 
observing by the way, that they have not yet been found in any portion of Western 
Europe, and that they have been rightly formed into a genus by the Russian authors 
Eichwald and Pander. 
1 One of these we named after our eminent friend M. von Buch. (See vol. ii. and bottom of the 
Table of fossils attached to the Map, PI. VI.) 
In some rare instances they reach to the size of three-fourths of an inch in diameter, particularly at 
Baltisch Port, in the cliffs of Esthonia. As in all sub-formations which constitute parts of a group, the 
Ungulite grit or sandstone passes in some situations into and alternates with the overlying calcareous 
strata. This observation was made by our friend M. Pander at Baltisch Port in Esthonia, from whence 
we have obtained rock specimens in which the sandy laminee with Ungulites are interlaced with impure 
limestone containing green grains and fossils of the overlying " pleta.” At Briggetten Kloster and 
Baltisch Port, the Ungulite grit has been found by Pander to be occasionally a pebbly rock, in parts of 
which are pebbles of white quartz, but the greater number of the included fragments consist merely of 
rounded schist. 
