CLARK: NEW FOSSILS FROM NEAR BOSTON. 483 
from this outcrop; and in this connection it is obvious that e\d- 
dence from unassorted drift is more desirable than that from 
eskers, kames, etc., whose materials may have been shifted 
considerably to one side or the other of the path of glacial motion 
by the waters which deposited them. Unless this relation be- 
tween erratics and parent ledge be established, the evidence, 
though valuable, loses much of its force through its very indefinite- 
ness. Thus in the article on fossils from Revere Beach, it has 
been impossible to assign a specific location where those fossils 
occur in situ. 
The rock to be described here was picked up on the beach at 
Crow Point, Hingham, Massachusetts, near the wharf, at the 
foot of the drumlin whence it was certainly derived. It is a 
fragment of shale 19 cm. long, 11 cm. wide and 1.5 cm. thick, 
breaking easily along the stratification planes. A great many of 
the boulders from this drumlin are of shale, many more in pro- 
portion than from other drumlins. This finds a ready explana- 
tion in the fact that about one mile to the northwest lies Slate 
Island, an island composed almost wholly of ledges of shale and 
slate. It seems almost certain that this thin slab of shale was 
brought by the glacier from the Slate Island ledge, especially as 
it is identical lithologically with the shale of that place. This 
conclusion represents as high a degree of probability as is possible. 
The rock is a finely banded shale with dark and light layers 
alternating, each about one millimeter thick; surfaces of the 
laminae are strewn with great numbers of elliptical markings from 
2 mm. to 20 mm. in diameter along their long axes, and all simi- 
larly oriented. These have many of the characteristics of Aspi- 
della,^ a so-called fossil described by Billings from the pre-Cam- 
brian of Newfoundland. 
In form these markings are identical with Billings' type 
material. They are surrounded by a raised ring within which is 
a sunken annular area from which the surface rises conically to a 
central apex or ridge. None of our specimens shows much i>lcva- 
tion, 2 mm. being the maximum. One shows radial lines such as 
Billings figured, but they are present on only one sitle. The 
markings are of all sizes between the limits stated; thev are about 
^ See Walcott, C. D. Tlio pre-Cainbiiaii fossiliforous formations. Bull. 
Gcol. See. Amer., vol. 10, p. 231, 1899. 
