1897.] Fossils and Fossilization. 193 
Kennebec River, Maine, the serpentine markings of what has 
been referred to a worm are well preserved. In the Medina 
sandstone, a red ferruginous sandstone of the Upper Silurian 
age, the fossils are poorly preserved, lacking fullness of contour 
and seldom showing the surface characters with any distinct- 
ness. Lyell collected oyster shells and Buccinum thrown up 
by a storm on the shore of the estuary of the Forth, Scotland, 
and observed that “although still living, their shells were 
worn by the long attrition of sand which had passed over them, 
as they lay in their native bed, and which had evidently not 
resulted from the mere action of the tempest, by which they 
were cast ashore.” The fossils of the Medina sandstone show 
abrasion, and in most cases present a rude cast of sand, made 
by the filling in of the shell, without muscular markings, and 
often with shrunken outlines, as if the sand filling had con- 
tracted. Wet sand, occupying the interior of a shell, must, upon 
drying, undergo some contraction, and being less apt to con- 
tract equally than clay or a calcareous paste, reproduces its 
mould less perfectly. The finer grained sandstone, however, and 
those somewhat more coherent, from the intermixture of lime 
or clay, are better adapted for the retention of fossil bodies and 
impressions. Thus, the Chemung sandstone (Upper Devonian) 
1$ a variable mixture of sand and carbonate of lime, and is in- 
troduced in a series of shales and siliceous limestones, whereby, 
as it formed a contiguous beach deposit to these, it became a 
Tepository of fossils, and was from its constitution better adapted 
to retain them. Mosely observed in the beach of Little Saba 
Island that there was being formed a reddish sandstone con- 
glomerate rock, made up of the débris of the rock of the higher 
parts of the island cemented together by calcareous matter, 
derived from the corals and calcareous sand. And in this 
forming mass, which made a hard compact rock, there were 
embedded “ plenty of the various corals from the beach, and 
large Turbo shells (T. pica) with their nacre quite fresh in lustre, 
and their bright greenish color unimpaired.” Something 
Similar is seen in the Chemung flagstones, and in the fossili- 
ferous layers of this group of beds the organic remains are 
plentiful and well preserved. In the Catskill sandstones, which 
