170 
THE GEOLOGIST. 
escaping for ages into the upper air, was condensed, and fell in the shape 
of snow and hail. By this mass of snow and hail the temperature of the 
earth's climate was reduced from the comparative warmth which preceded 
it, even in Arctic regions, and the world entered on ' the cold period,' which 
it was the object of the lecturer to describe and to account for while de- 
scribing. Professor Agassiz said that this was the lointer ivhich preceded 
mans advent in the world " 
Is not my point made out ? Is not the thohu and vohu of Moses iden- 
tical with the cold peynod, the tvin ter of the world, of Agassiz ? Surely there 
can be only one answer. 
It seems almost superfluous to refer to the boulders which are found in 
Norway and on the coasts of north-western Europe, which evidently be- 
long to the period of the Drift, and which have been borne to the spots 
where they are now found on moving ice. 
I think. Sir, your readers must allow that my point is clearly made out, 
namely, that Moses and the geologists are of one mind as to the deplorable 
condition of the earth at tlie time when the Mosaic record and geology 
come in contact. I have the honour to remain, Sir, 
Your obedient servant, 
Feedekick Ftsh. 
Walgrave, April 7, 1864. 
P.S. I take the meaning of the fourth day's creation to be, that the 
sun, moon, and stars, which had been previously obscured, then became 
visible. Henceforth the earth was to receive light from those luminaries, 
and not to be supplied with miraculous light, as on the first day. 
The Scottish Fteraspis. 
Dear Sir, — If not occupying too much space, I would feel obliged by 
your inserting in an early number the following remarks on the communi- 
cations in your numbers for March and April from the Rev. H. Mitchell 
and Mr. E. K. Lankestcr ; these I have the less hesitation in offering, as, 
while fully appreciating the value of the criticisms of one who has done so 
much towards adding to our knowledge of this genus as Mr. Laukester, I 
can at same time fully corroborate the correctness of Mr. Mitchell's re- 
storation, in his interesting letter, in almost every particular. 
In a former letter (Geol. Feb. 1863) I had occasion to remark that Mr. 
Lankester, in a notice (Dec. 1862) of a former and much less correct re- 
storation of our Scottish Pteraspis by Mr. Mitchell (Nov. 1862), had not 
made sufficient allowance for probable specific difference of form. I must 
here state my belief that the same mistake has again occasioned some of 
Mr. Lankester's remarks in his last letter. I had recently an opportunity 
of inspecting Mr. Mitchell's series of specimens of this fish, and of com- 
paring them with my own. They all undoubtedly belong to tlie same 
species, and are in my opinion distinct from Pteraspis rostratus and other 
iilnglish species. 
The only points in Mr. Mitchell's latter restoration which appear to me 
scarcely correct are, that the breadth seems rather exaggerated, and that 
the posterior margin is represented as formed of straight lines, while it 
consists of a double curve, concave posteriorly. The lateral posterior 
angles are produced, forming well-marked but very short cusps, pointing 
backward and slightly outwards. From this and also from the well-marked 
