ECIIINOID GENUS ECHINOCOIÎYS

GENUS ECHINOCORYS IN THE SENONIAN OF BELGIUM 13
which connect it to a vulgaris var. striata-\ike form on the one hand and to other
later representatives of the genus on the other, are further substantiated by the
fact that stratigraphically it is prominent in the earlier divisions of the chalk. It
is for example a quite important element in the Echinocorys fauna of the Graie de
Triviere, continues in importance in the Crate d'Obourg and diminishes to a
relatively insignificant position in the later Echinocorys faunas.
FIG. 2 o-d. — Echinocorys marginatus. (a) Contour (b) longitudinal profile (c) transverse
profile of a specimen from the Craie d'Obourg; figured specimen Musée d'Histoire Naturelle,
Brussels (I. G. 6435), the same specimen figured by Lambert ((f) longitudinal profile
of the Goldfuss marginatus, an example from the Craie de Trivière at Harmignies; figured
specimen Musée d'Histoire Naturelle, Brussels.
The second group are dome-like and symmetrical in longitudinal profile on
the upper surface, although sometimes the summit portion is a slightly flattened
curve.
Anterior and posterior slopes abrupt and the outline or contour of the
test broadly oval with often a tendency toward the development of a gentle
carina. The group is well represented by Lambert's figured specimen (see
figure 26 above).