_1848.], SIR P. EGERTON ON PTERICHTHYS. 303 
the kindred branches of Paleeontology. Unfortunately I have neither 
the talent, the means, nor. the time to grapple with so vast a subject 
on a scale commensurate with the requirements of science; I am 
nevertheless anxious. to render what services I can, subject to these 
limitations, to the general fund of knowledge. I propose therefore 
to communicate to the Society, from time to time, notices on fossil 
fishes, which may be considered supplemental and auxiliary to the 
works of Professor Agassiz. They will contain characters of new 
genera and species, corrections and amplifications of previous descrip- 
tions when warranted by conclusive evidence, and intimations of and 
reference to ichthyological discoveries recorded by other authors, 
British and foreign. Such communications can hardly be presented 
in a form interesting to the general reader; they may nevertheless 
prove worthy of a place in the Journal of the Society, as being useful 
for general and special reference ; they will also greatly facilitate the 
labours of Agassiz, when he resumes his promised series of mono- 
graphs, in continuation of his great work on Fossil Ichthyology. 
The subject of the first notice is the family of Cephalaspides, 
commencing with the genus Pterichthys, m the preparation of which 
I have had the advantage of the valuable co-operation of Mr. Hugh 
Miller, the original discoverer and interpreter of the materials out of 
which this strange group of fishes has been elaborated. 
Family CEPHALASPIDES, Genus PrericutTuys. By Sir Puiuip 
Grey Ecerton and Mr. Hueu Miuuer. 
On perusing the description of the genus Pterichthys given at page 9 
of the Monograph on the Fishes of the Old Red Sandstone, I cannot 
divest my mind of the suspicion that Agassiz has inverted the order 
of nature and assigned a supine position to the ventral surface of the 
fish. The reasons which have engendered this doubt (for I am loath 
to advance a positive opinion in contravention of such high authority) 
will appear in the sequel. I may premise that I am not smmgular in 
the view I take of the relative position of parts in the dermal economy 
of this genus, for Mr. Hugh Miller, the original discoverer of these 
enigmatical organisms, with the intuitive talent so conspicuous in his 
very original little volume on the Old Red Sandstone, has described 
and figured this curious fish in two positions, showing the arrange- 
ment of the plates both on the back and belly. The sketch is so 
graphic, and at the same time so correct, that I cannot refrain from 
quoting the passage :—‘‘The body,” says Hugh Miller, “was of 
considerable depth; * * * the under part was flat, the upper rose 
towards the centre into a roof-like ridge, and both under and upper 
were covered with a strong armour of bony plates. * * * The plates 
on the under side are divided by two lines of suture, which run, the 
one longitudinally through the centre of the body, the other trans- 
versely, also through the centre of it ; and they would cut one another 
at right angles, were there not a lozenge-shaped plate inserted at the 
poimt where they would otherwise meet. * * * The plates on the 
upper side are more numerous and more difficult to describe, just as 
it would be difficult to describe the forms of the various stones which 
