156 
THE GEOLOGIST. 
Meptana lata and depressa, Orthis lunata, and Terehratula nucnla : 
the T. navicula seems to have died out suddenly, as it is not 
found in the Upper Ludlow beds. 
The same division of the Ludlow rocks may be obtained by 
attending to the direction and dip of the beds ; the lower series 
partakes of the north-east strike, which runs through the older 
Silurian rocks in these counties, and is traversed by many of 
the same faults as those formations, but the Upper Ludlow 
beds are thro\^Ti up in anticlinal ridges with a different direc- 
tion. 
Mr. Sharpe gives a list of the organic remains found in each 
division of the formation, which includes forty-four of the species 
described in Mr. Murchison^s work from the old red sandstone 
and Upper Ludlow, fourteen of those from the Aymestry lime- 
stone, and twenty-two of those from the Lower Ludlow beds. 
Of the species of shells placed by Mr Murchison in the old 
red sandstone all but two have now been found in the 
Ludlow beds, proving that the red beds containing these spe- 
cies in Herefordshire must be classed with the Upper Ludlow 
formation. 
Old Red Sandstone. — The only addition to the former paper 
which relates to this formation, is in mapping it in the upper 
valley of the Lune, where the tile-stones reach above the hamlet 
of Langdale, dipping N.N.E. 10°. 
The age of the large masses of gravel of a brown and red 
colour noticed in the valley of the Lune between Sedberg and 
Casterton, and of the Kent and Sprint, was before left uncer- 
tain ; the author now regards them as a modern surface drift. 
Mountain Limestone. — The description of this formation did 
not enter into Mr. Sharpens plan but he examined the portion of 
it which occurs in Low Furness, to ascertain the geological posi- 
tion of the Ulverston iron ore. 
* Silurian System, p. 603, and t. 3. 
