BOULDER-CLAY AT BRIDLINGTON QUAY. 315 
The fauna of the masses also varied greatly. Some contained 
many shells throughout ; others very few, occasionally none ; others 
had shells in one part, but not in another; and one mass, that 
marked C on the plan, seemed to be of freshwater origin, as it con- 
sisted of very fine unctuous slaty-blue clay without stones or shells, 
through which ran a thin seam of peaty matter, in which traces of 
moss, wood, and the seeds of Potamogeton were detected. 
Further, when marine shells occurred, though a few forms such 
as Astarte borealis, Astarte compressa, and Saxiava rugosa were 
rarely absent, the greater number of species were either limited to 
certain masses, or occurred plentifully in one place and sparingly 
elsewhere; so that there was generally a well-marked difference 
between the fauna of adjacent masses. 
Most of the clay-patches showed a curious admixture of dark 
ereen sand, containing Foraminifera. This was usually diffused 
through the fine clay in thin and irregular beady streaks, as though 
thoroughly kneaded in; but here and there, especially in the mass 
marked B on the plan, isolated patches of this sand occurred amidst 
the clay ; boulders involved in a boulder. Wherever this sand was 
abundant shells were plentiful, and in these patches they were also 
best preserved. 
The sand itself contained many small black pebbles ; waterworn 
coprolitic-looking fragments of bone and fishes’ teeth; and coarse 
subangular grains of quartz. It is not, in my opinion, such as 
would form from the waste of any of our Yorkshire rocks. 
Although shells were plentiful in the masses, the great majority 
were so crushed and broken, and the fragments so scattered, that 
the ordinary method of collecting yielded extremely meagre results. 
But my friend, Mr. W. B. Headley, of this town, by removing a 
large quantity of the material and carefully washing, sifting, and 
examining it, obtained a very large and interesting collection, not 
only of molluscan, but also of fish and other marine remains. This 
_ collection he has very considerately placed at my disposal in working 
up the subject, and, by the help of the gentlemen elsewhere named, 
who kindly undertook the determination of the species, the lists 
which form appendices to this paper have been drawn up. From 
these it will be seen that Mr. Headley’s work has resulted in large 
and important additions to our knowledge of the fauna of the deposit, 
the number of known species of Mollusca alone being raised from 
67 to 83, five of the additions being new to science; and the lists 
of fish and other fossils are almost new. There still remain a few 
fragmentary corals, Echinoderms, and Polyzoa which have not been 
determined. 
Special interest attaches to the state of preservation and mode 
of occurrence of the shells, as it is their condition which has caused 
the deposit to be described, and still occasionally considered, as a 
bed in place*. As I have just mentioned, the great majority of 
the shells were crushed into fragments, and these generally some- 
* Mr. 8S. V. Wood in Quart. Journ. Geol. Soc. vol. xxxvi. p. 516, and letter 
sup. cit. 
