ENVIRONS OF NICE, 443 
or a pale bluish-grey ; both are mixtures of argillaceous and 
calcareous matter. The former often occurs without the lat- 
ter, and when together, it always assumes the uppermost situa- 
tion. Of the blue clay bricks and tiles are manufactured, and 
I think it might be applied with success to the fabrication of 
pottery, as it forms a tough adhesive paste when kneaded with 
water, and is of a delicate pale-red colour when burnt. 
It is in this particular kind of clay that a considerable varie- 
ty of shells are found, of kinds also which are all to be met 
with alive in the Mediterranean. A few of them I found in the 
most perfect state cf preservation ; but in general they were so 
much decomposed, that it was very difficult to withdraw them 
from the clay. In almost every valley, these deposites are to 
be found, and although some kinds of shells may prevail more 
in one than in another, still they are throughout generally the 
same varieties, and possess a character peculiar to the clay in 
which they occur. 
In one situation, where the deposite was simply of sand, and 
not many inches thick, I found a great quantity of bivalve 
shells, principally pectens, and other small kinds of the ostrea, 
_. but not one univalve. In the particular situation I now allude 
to, I have no doubt that the shells were in a very recent state, 
if not alive, when they were left by the sea. It is true, that 
for one unbroken which I found, I threw aside the fragments 
of hundreds; yet it seems to be impossible, that shells so deli- 
cate and so minute, could submit to the action of transporta- 
tion. Besides, the quantity that are here found together, be- 
speaks the probability of an original bed. Oysienshend J Have 
observed in the same bank, sf so perfect a state, that I could 
not have believed them to be any thing but recent, had I not 
disengaged them with my own hands. Some of them were 
attached to pieces of gravel, not agglutinated by means of cal- 
83K 2 * careous 
