MITCHELL ON THK FLAGSTONES OF FORFAESHIRB. 
147 
have made already, though not nearly sufficient to clear up many 
highly important questions, are still sufficient to give very great 
encouragement ; and I therefore feel anxiois to induce others to turn 
their attention to this branch of research, being convinced that it 
cannot but yield a bountiful harvest of facts, when studied with 
perseverance and zeal. 
ON THE FLAGSTONES OF FORFARSHIRE. 
By Hugh Mitchell, of Craig. 
There is a close resemblance between the fossil contents of the 
" Upper Ludlow Tilestones," as described by Mr. Roberts, of Kidder- 
minster, in the last number of The Geologist, and those of certain 
strata developed in this neighbourhood. The rocks of the southern 
districts of Forfarshire have been described by Fleming and Miller, 
and their fossils have atti'acted the attention of the scientific world. 
I am acquainted with sections in the north-eastern division, an account 
of which has not yet appeared in print, and it may be of interest to 
indicate their organisms. 
Among our fish-remains I have twice met with heads of the CepJial- 
aspis Lyellii ; but the fossil is more common in other localities. The 
Pteraspides, which seem to be so frequent in the English beds, I do 
not know, unless some of the fragmentary remains, like pieces of skin 
or shell, and to which I shall hereafter refei', belong to the genus. 
From one of our sections I have collected several specimens of at least 
two species of fishes, entire and beautifully preserved. They are small 
creatures, and have all their fins armed with spines. One of my 
specimens is a very tiny fish, scarce an inch in length, but with its 
every spine in its place, and, so far as regards its dermal covering, a 
complete picture. We have also a considerable variety of Ichthyo- 
dorulites. Some of them resemble the Onchus-spines figured in the 
first edition of Sir Roderick Murchison's " Siluria." Others are larger 
and have more the appearance of true fish-defences. Mostly all our 
fossils are mere impressions in the stone ; but the bony matter of the 
