ECIIINOID GENUS ECHINOCOIÎYS

GENUS ECHINOCORYS IN THE SENONIAN OF BELGIUM 35
Echinocorys orbis
ARNAUD.
Echinocorys orbis LAMBERT, 1903, Étude monog. sur le genre Echinocorys. (Mém. Mus.
roy. d'Hist. nat. de Belg., n° 8 [in vol. 2], p. 68, pl. 1, figs. 18-20.)
This species is rare in Belgium and some individuals are difficult to separate
from I heir near relarives, the variety minor of E. conicus. Obviously the typical
forms are distinct but one must realize that all gradations het ween conicus
minor between these and orbis exist.
and
FIG. 17 a-c. — Echinocorys orbis. (a) contour (b) longitudinal profile (c) transverse
profile of a specimen from the Craie d'Ohourg at Hannignies, figured specimen Musée
d'Histoire Naturelle, Brussels (I. G. 6435). Same specimen figured by Lambert.
E. orbis is small, subglobose with inflated sides, rounded borders and
swollen base. The upper surface, near the apex, is low but there are forms in
every respect like orbis but with a rather sharp variety minor-like apex with the
depression of the slope just posterior and with the apex still more central and
not so far anterior as in minor. On a whole the species is distinguished most
easily by the general rotundity of the test, smoothly rounded at nearly all points,
low, and with the flanks passing into the base with less angularity than in any
other related species or variety.
OCCURRENCE : This rare form has been found only in the Craie d'Obourg in
Belgium at Hannignies.
Echinocorys conoideus
GOLDFUSS (Ananchytes).
Echinocorys conoideus GOLDFUSS, 1826. Petref. Germaniae, p. 145, pi. 44, fig. 2.
Characterized by its great height, evenly convex summit, flat base ornamented
with prominent scrobiculate tubercles and showing a prominent plastron.
The sides are steep but declivitous not inflated, borders angular and the contour
sometimes subcircular but ordinarily broadly oval. The upper surface with