81 8 
The Rev. Mr. Yates on the Curl , £sf<r. 
Mr. Sowerby has given two representations of this mineral in his 
British Mineralogy (vol. II. plates 148, 149); and we are there in- 
formed that it occurs near Sunderland, at Bartonfel in Cumberland, 
at Boulby in Yorkshire, and in Derbyshire. The variety found in 
Derbyshire is described and figured in Martin’s Petrificata Derbiensia 
(Wigan, 1809) plate 27, fig. 4. It is found immediately above 
and attached to a stratum of iron-stone which extends from Tupton 
Moor to Staveley. 
In the collection of the Geological Society, are specimens from 
the clay-slate from the vale of the Dyfy, near Machynlleth, in 
Merionethshire. They differ very considerably from the Stafford- 
shire and Shropshire specimens in fracture, in colour, and in the 
size of the distinct concretions. 
From the information of Dr. G. Forchhammer, I am also enabled 
to state, that this substance (to which Werner, not long before his 
death, gave the name of dutenmergel , or funnel marl ,) is found at 
G’ororp’s Mill in Shoenen, and in the island of Bornholm, near 
the town of Ronne. It occurs at those places in a coal-formation, 
and is attached to a stratum of sandstone. 
