340 
SILURIA. 
[Chap. XIII. 
Devonian strata, and which has very seldom been found in the Carboniferous 
rocks of England, has not yet been detected in Permian deposits. In unison, 
however, with the prevailing law of nature, which, in modifying beings at suc- 
cessive periods, often retained some features of the preceding types, the Penta- 
merus is represented in the Permian division by the curious terebratuloid 
shell nameo^ Camarophoria by Professor King, which offers in its internal ar- 
rangement an approach to the structure of the Pentamerus. One of the most 
frequent Permian shells, indeed, is Camarophoria Schlotheimi, von Buch, figured 
in the work on Russia, vol. ii. pi. 8. figs. 4, 5. This singular Brachiopod also 
disappeared at the close of the Permian era, and its place was occupied by genera, 
such as Terebratula or Rhynchonella, which exist even in the present day. 
It is worthy of note that, of the eighteen Permian Brachiopods which are 
known in Britain, fifteen occur in the same strata in Germany ; whilst among 
them are certain species, seven in number, which extend their range even to the 
north-eastern extremity of European Russia. 
The following Table, published by the distinguished palaeontologist Mr. T. 
Davidson, shows this distribution of the Permian Brachiopoda in Britain, Ger- 
many, and Russia * : — 
List of the chief British Permian Brachiopoda. 
In the Magnesian Limestone of Britain. 
Occurring also in 
Germany. Russia. 
Terebratula elongata, Schloth., var. sufflata ... 
Spirifer alatus, Schloth 
Spirifer Clannyanus, King 
Spiriferina cristata, Schloth 
Spiriferina multiplicata, Sow 
Athyris pectinifera, Sow 
Camarophoria Schlotheimi, von Buch 
Camarophoria globulina, Phillips 
Camarophoria Humbletonensis, Howse 
Strephorhynchus pelargonatus, Schloth 
Productus horridus, Sow 
Productus latirostratus, Howse 
Strophalosia Groldfussi, Minister 
Strophalosia lamellosa, Geinitz, var. Morrisiana 
Crfenia Kirkbyi, Dav. 
Discina Koninckii, Geinitz 
Lingula Credneri, Geinitz 
Chonetes Hardrensis, Phillips. 
In the Lamellibranchiate Shells (the Dimyaria and Monomyaria), we note the 
same diminution of genera and species in reference to deposits of previous eras ; 
and whilst not less than 288 species are known in the Carboniferous, about 73 
only have been obtained in the Permian deposits. Myalina and Schizodus 
(King) are characteristic genera ; Myalina Hausmanni and Schizodus Schlotheimi 
are abundant in the Upper Magnesian Limestone and Zechstein. S. obscurus 
and S. truncatus prevail in the lower strata of the series; and occur also in 
Russia. The genus Gervillia is also abundant, G. antiqua and G. keratophaga 
being very common in Western Europe. Another Aviculoid shell, now referred 
to Monotis (M. speluncaria), is wide in its range. Keyserling foimd it on the 
banks of the Pinega in the Province of Archangel ; and it occurs in Germany, 
* See Monograph of Permian Fossils : Palseontograph. Soe. 1858. 
