7o REPORT—1850. 
GEOLOGY AND PHYSICAL GEOGRAPHY. 
On the Fossil Fishes and Yellow Sandstone of Dura Den. 
By Dr. ANDERSON. 
Dura Dew occupies a central position in Fifeshire, and consists of the upper old red 
sandstone formation. The geological relation of the beds is well-marked and defined. 
They repose on reddish strata, of a fine as well as conglomerate texture, similar to 
those which occupy the basin of the Tay, and which are charged with organisms of 
the same character. The carboniferous deposits overlie and crop out in the im- 
mediate vicinity. The irruptive rocks form the line of separation, which have tilted 
up the latter to an angle of 26°, while the yellow sandstone is nearly horizontal, or 
inclining to the S.E. at an angle of 6° to 8°. 
This interesting deposit traverses the valley of Stratheden, in the district of which 
Cupar, the county town, forms the centre, and rises to the height of 500 or 600 feet 
on the ridge of hills which skirt the valley on the south. The colour of the sand- 
stone is grayish-yellow, often iron-shot, and exhibiting in some localities a deep red- 
dish tinge. Some of the beds are coarse and gritty, and occasionally pass into a 
conglomerate; but for the most part they are of a fine texture, and extensively used 
for building purposes. The whole are interstratified with thin micaceous flaggy beds, 
which pass into a kind of shale or marl, and being of various colours, as red, blue, 
and white, give to the face of the rock a variegated appearance. The coloured marl 
beds are, some of them, four feet thick, and entirely destitute of organisms. 
The organic remains are chiefly confined to the lower beds, and consist, according 
to Agassiz, of the following kinds:—Holoptychius Andersoni and Flemingii, Glypto- 
pomus minor, Platygnathus Jamesoni, Pamphractus hydrophilus and Andersoni (the 
Pterichthys of Sir Philip Egerton). In addition to these, the same eminent ichthy- 
ologist has marked on specimens in the author’s collection, a Diplopterus, new 
species ; Glypticus, new genus, of which there are two species; and Dipterus, new 
species. The specimens presented along with the paper contain two or three entirely 
new generic forms. This remarkable deposit is, in many places, filled to repletion 
with these fossil remains, which are all in the most perfect state of preservation, and 
start from the matrix on the slightest stroke of the hammer. The author concluded 
a long and interesting paper, by calling upon the Chairman, Sir R. 1. Murchison, to 
assign to one of the new and undescribed fossils the specific name of Dalgleisiane, 
in honour of the proprietor of Dura Den. 
On a Fossiliferous Deposit underlying Basalt in the Island of Mull. 
By the Duke of Arcy.t. 
It occurred on the headland of Ardtun, in the S.W. end of the island. The 
headland is about 130 feet high, and is composed as follows, reckoning from the top 
downwards. 
I. Basalt, rudely columnar. 
II. First leaf-bed. 
III. Tuff, or volcanic ashes, being thickly disseminated with while lapilli, imbedded 
in a pumiceous ashy paste. 
IV. Second leaf-bed, about eighteen inches thick, and consisting in its lower part 
of pure compressed vegetable matter. 
V. A second bed of tuff, or volcanic ashes, passing into a conglomerate of flints, 
water-worn, and containing some organic remains of the chalk flints. 
VI. Third leaf-bed, thinner than those above. 
VII. A thick bed of amorphous, amygdaloidal basalt. 
VIII. Basalt, beautifully columnar; the columns being smaller, but as regular as 
those of Staffa, and dipping into the sea. 
The leaves found in the fossiliferous deposits thus situated are of a considerable 
variety, being for the most part dicotyledonous plants. Many of the finest specimens 
obtained are of the Platanus family. Good specimens of the Pine-tribe also occur. 
Associated with the leaves, eopesially in the lower part of the second leaf-bed, many 
