466 
that, by the assistance of Mr. Lonsdale, he has been enabled to as- 
certain that the fossils contained in the transition rocks of the islands 
and shores of the fiord of Christiania agree most nearly with those 
in the lower part of the English Silurian system; and, Mr. Lyell 
adds, that in mineral character the Norwegian rocks also resemble 
more closely that part of the system as exhibited in Shropshire and 
Radnorshire than the upper. 
The two principal divisions of the Christiania group consist, first, 
of dark shale, slate and clay, some of the beds being highly calcareous, 
- and enclosing Graptolites, Trilobites and other fossils; also of beds 
of grit; and secondly, of strata of smoke-grey limestone abound- 
ing in corals, and of sandstone, shale and conglomerate. Prof. Keil- 
hau, who has long studied these formations, of which the beds are 
much disturbed, inclines to the opinion that the second division is 
the uppermost deposit. Among the fossils common to the Chris- 
tiania series and the English lower Silurian strata are Culymene punc- 
tata, Trinucleus Caractici, Orthoceras conicum, Bellerophon bilobatus, 
Pentamerus oblongus and Graptolites Murchisonius: other species of 
Trilobites, which are not British, partake of the same type as those 
which characterize the Caradoc sandstone or Llandeilo flags. 
In the island of Langoen in the fiord of Christiania, a few miles 
from Holmstrand, Mr. Lyell examined a limestone rich in fossils. 
It dips regularly towards the west, or in the direction of Holm- 
strand; and he believes that it constitutes, together with the quartz- 
ose sandstone near that town, one of the uppermost divisions of the 
Christiania formation. Among the corals which he obtained from 
the limestone, the following have been determined as identical 
with British species ; and as five of them have been found in En- 
gland, hitherto, only in the upper Silurian strata, and others both in 
the upper and lower, Mr. Lyell is of opinion that the Langoen deposit 
may indicate a passage from the lower to the upper Silurian rocks. 
Stratigraphical position in the English 
Genus and Species. Silurian System. 
Catenipora escharoides .... Aymestry limestone to Llandeilo flags. 
Ptilodictya lanceolata... .... Wenlock limestone. 
Stromatopora concentrica .. Wenlock limestone and shale. 
‘Fayosites Gothlandica ....Aymestry limestone to Caradoc limest. 
fibrosa ..... 2 1): Dittos ditto. 
polymorpha? .. Upper Ludlow and Aymestry limestone. 
Limaria fructuosa ........ Wenlock limestone and shale. 
Millepora? repens........ Wenlock limestone. 
The same beds also contain Huomphalus subsulcatus, Producta 
euglypha, and Cytherina Baltica. 
A series of fossils lately obtained at Christiania by Mr. Bunbury, 
lead to precisely similar results*. The total number of species con- 
* Mr. Bunbury has informed Mr. Lyell that Asaphus expansus, Illenus 
crassicauda and a Spheronites, common in the Silurian strata of Christiania, 
are also characteristic, according to M. de Verneuil, of Silurian beds near 
St. Petersburg. These species are apparently unknown in England, but 
My. Lyell suggests that the Russian strata containing them will probably 
prove to be lower Silurian. 
