52 REPORT—1846. 
and Finland, bringing cold water and masses of ice into the German Ocean, which 
being at that epoch a bay receiving waters also which had flowed round the northern 
coast of Scotland, must have been materially influenced in its climate, so as to have 
been colder than it is now. f 
On the Fishes of the London Clay. By M. Acassiz. 
The Professor stated that since his last report the number of species known from | 
the Paris basin increased; whilst few new forms had been obtained in the London 
clay. He had however been interested in the examination of specimens of the teeth 
of the saw-fish (Pristis) ; and had noticed some curious changes which they under- 
went during the growth of the animal. The young teeth were covered with enamel, 
and had a notch in their posterior margin; whilst in old tusks the bony material 
alone existed and the margin was entire. On these grounds he considered the 
three species of Pristis described by Shaw (P. semi-sagittatus, microdon and cuspi- 
datus) as constituting in reality only one. Widely as these teeth differed in appear- _ 
ance from the flat, pavement-like teeth of the Sting-rays (Myliobatis), their micro- 
scopic structure was identical; and Prof. Miiller of Berlin had lately shown that 
the Pristis was not a shark, but belonged to the family of Rays. The Professor 
then pointed out a peculiarity in the construction of the ventral fins of the Medi- 
terranean Goby, a fish which fixes itself to the bottom by its fins; that act also like 
springs in enabling the fish to rise from the bottom. He expected soon to be able 
not only to discriminate every individual bone of any importance in the skeleton of 
a fish, but also to distinguish the separate fin rays. M. Agassiz then made some 
general remarks on the geographical distribution of recent fishes. There were many 
families—of which the flying-fish (Exocetus) was an example—which were found 
equally in the Indian, Pacific, and Atlantic Oceans. Others, like the Sharks and 
Rays, were found in every sea from the Arctic circle to the tropics, but the species 
differed on each coast; whilst some families were confined to the Indian seas, and 
co-extensive only with the great land animals of that region. The Goniodontes 
were peculiar to the freshwaters of South America; but these were connected with 
the Ganoides of North America ; and these again closely allied to the Sturgeon, whose 
affinities have hitherto been little understood. We have here, confined to the New 
World, all the representatives of an order widely dispersed over the ancient strata. 
Looking at the distribution of a particular species, like the Silurus, confined to the 
Danube, Rhine, and a few other freshwaters of Europe, it might be asked by what 
means it had wandered from one locality to another; to which he would reply that 
these freshwater fish must have been created in the very streams in which they now 
live, and in the same proportion as now. They leave the egg in so short a time, that 
it was quite impossible they should be transported by birds or otherwise. The fishes 
in the Paris basin appeared to have lived on a coral reef or rocky bottom, whilst 
those of the London clay were such as in existing seas are found in shallow seas 
and muddy waters. 
On the Artesian Weil on the Southampton Common. 
By J. R. Keerz, M.R.CI. 
It will be seen on reference to the map that Southampton is situated about the 
middle of a tertiary basin, and in its geological position is not very different from 
London or Paris. The supply of water hitherto obtained has chiefly been from 
private wells: almost every house in the town of any pretension as to size or value 
has one, varying in depth from 10 to 25 feet. It is not known that any well 
in the town exceeds that depth, since beyond that point, in most parts of the 
town, we enter the bed of London clay, which lies under the whole district. There 
is also a fluctuating supply obtained from the Common, about a mile-and-a-half 
or two miles from the town. The extent of the Common is about 360 acres, and 
its elevation varies from 100 to 200 feet above the sea-level of the town; the 
quantity of water got from this quarter has been gained by intersecting the Common 
in various directions by drains of varying depth from 10 to 20 feet: the water 
thus collected flows into three reservoirs, from whence it is conveyed into the town 
by iron pipes. This supply is variable according to the season; in the winter 
