228 CATALOGUE OF THE FOS, ILS OF THE PERMIAN SYSTEM 
formation. It would appear from this that no material change 
in the marine fauna took place during the whole time the lime- 
stone was being deposited, and further, perhaps, it may be safely 
concluded that a very correct representation of the marine fauna 
that actually existed during this period, is still preserved in these 
rocks. . 
The greater part of the shells found in the fossiliferous bed are 
of full sized individuals, and from the circumstance of a Serpula 
and a Spirorbis having grown to the internal surface of many of 
them, they must have been some time dead before they were 
finally embedded. Generally, the bivalves are either entirely 
separate or slightly opened, and the plates of a Chiton are found 
at considerable distances from each other. Some of the corals 
are broken into small pieces and much spread about; and the 
joints of an Encrinite are strewn all through the bed. The shells, 
however, do not appear to have been in the least broken, and 
very few of them have been worn by the action of water. A 
conclusion from these appearances may be safely drawn that this 
bed was quietly and gradually deposited. 
If the shells enumerated in the list are carefully examined it 
will be found that most of them are referrible to genera which 
live either on the coast or in water of moderate depth, and, there- 
fore, as the most common and characteristic forms bear a de- 
cidedly littoral aspect, it seems only right to infer that this bed, 
at least, was deposited in comparatively shallow water, and at no 
great distance from land. 
It was long since asserted by several eminent Geologists, 
that the fauna of this formation bore a greater resemblance to 
those of the Carboniferous and the older rocks generally, than 
to others of more recent date.* This opinion has lately been 
fully established by a careful comparison of the faunas of these 
rocks in different parts of Europe with each other, and with 
those of the older and of the more recent systems.t In this exa- 
mination several allied species are supposed to occur in all the 
older rocks from the Silurian up to the Permian system inclu- 
* Sedgwick, Geol. Tr. 2nd ser., iii., p. 99; Phillips, Palasoz. Foss. p. 165. 
+ Geology of Russia, Vol. I., p. 199. 
