PERMIAN BRACHIOPODA. 
245 
Chonetes Davidsoni was first discovered by Mr. Kirkby, along with large examples bf 
Sp. TJrei and Camarophoria crumena, in a light yellow Lower magnesian limestone at 
Hartley's Quarry, Millfield, Bishopwearmouth, Sunderland. Baron Schauroth's specimens 
were fomid in a similar kind of rock (Mergelschiefer of Ilmenau). Both the English and 
German specimens are of a white colour, due to the matrix, and vary considerably in 
shape. 
Mr. Kirkby informs me that " the Brachiopod that appeared first in the Permian 
formation of the north of England is Linrjula Credneri, which is found in a thin, irregu- 
larly deposited, sandy marJ, full of pebbles, that rests on the Coal-measures, at East 
Thickley and Midderidge, in Durham. The bed is only two or three inches thick ; the 
Lingulse are numerous and fully larger than in the Marl-slate above ; and occasional 
examples of Monotis speluncaria, Sclilotheim, occur with them. - ■ 
In the Makl-Slate Lingula Credneri is a common fossil in certain localities in South 
Durham ; Discina Koninclcii sometimes occurs with it. 
Lower Limestone. — These species range up for some distance into the thin lime- 
stones that overlie the Marl-slate ; and as the limestone becomes purer are gradually 
joined by Productus horridus, Strophalosia lamellosa, 8. Goldfussi, Streptorhi/nchus pelar- 
ffonatiis, Chonetes Davidsoni, CamaropJioria crumena, Terebratula elongata, Atliyris pec- 
tinifera, Spirifera alata, iS. Urei, and Spiriferina imdtip)licata. In some localities these 
Brachiopods are not rare, and are pretty well developed. This remark more particularly 
applies to the localities of Whitley, certain beds at Hartley's Quarry, and at East 
Thickley, in Durham, and to the quarries near Nosterfield in Yorkshire. But, as a rule, 
Brachiopods (as well as other fossils) are not rife in the lower division of this formation, 
and occur in a badly preserved and somewhat dwarfed condition. The species which 
most repeatedly occur are StropjJialosia lamellosa, Terebratula elongata, and Productus 
horridus. 
The Middle or Shell Limestone. — It is in the middle division of the formation, 
as developed in North Durham, that Brachiopods (along with other forms of marine life) 
are best represented. Of the eighteen species found in the formation in Great Britain, 
sixteen occur in this portion of it, and in certain localities (Tunstall Hill, Humbleton 
Hill, and Byhope Eield House) in great abundance. Terebratula elongata, Spiriferina 
multiplicata, Camaroplioria crumena, C. glohidina, Productus horridus, and Strojjhalosia 
Goldfussi, are perhaps the most common and characteristic. 
In the Upper Limestone of Durham, as well as in the middle and upper divisions 
of the Magnesian limestone, in Yorkshire, no Brachiopods have been seen. Neither are 
they known in Permian deposits south of Yorkshire, or in the West of England, or any- 
where else in the British area except, possibly, in Warwickshire, where some curious 
sandstone casts have been thought to resemble Strophalosia^^ 
1 'Mem. Geol. Survey, Warwickshire Coal-Field,' p. 31. 
