Book Excerpt Entitled, "Genus Oncoceras"

GENUS ONCOCERAS, HALL.

In the first volume of the Paleontology of New York, I
have proposed a separation of the forms like Cyrtoceras, when
the aperture is abruptly constricted, and the apex more ab-
ruptly tapering from the middle of the shell. Some of the
forms are much like curved Gomphoceras, with a more extended
apex. The section is usually broadly elliptical and the
siphuncle dorsal, or on the outer side of the curve.

The contraction towards the aperture is often extreme, and
in all individuals which I have seen, this feature is strongly
marked. The genus is at least convenient for the reference of
species of this peculiar type.

Hall, Geol. Rep. Wis 1861 p 43

GENUS ONCOCERAS, HALL.

In the first volume of the Palalontology of New York, I
have proposed a separation of the forms like Cyrtoceras, when
the aperture is abruptly constricted, and the apex more ab-
ruptly tapering from the middle of the shell. Some of the
forms are much like curved Gomphoceras, with a more extended
apex. The section is usually broadly elliptical and the
siphuncle dorsal, or on the outer side of the curve.

The contraction towards the aperture is often extreme, and
in all individuals which I have seen, this feature is strongly
marked. The genus is at least convenient for the reference of
species of this peculiar type.

Hall, Geol. Rep. Wis 1861 p 43