ECIIINOID GENUS ECHINOCOIÎYS

GENUS ECHINOCORYS IN THE SENONIAN OF BELGIUM 33
Echinocorys lambertl, it must be realized, varies some but within a limited
range. For example, the posterior is often very prominent, more so even than
in fastigata and often nearly pointed; some more closely resemble conicus in this
character; but all in all the form is so much smaller than the true conicus, flanks
much less inflated than the latter, and never shows the extended anterior border
of fastigata. The species is here defined to include the variations from the type
shown in figure 14a (and in pi. 2, fig. 3) to the extreme type or end product as
shown in figure 14 b (and in pi. 2, fig. 4). This latter is the type which sometimes
exhibits the very prominent apex.
OCCURRENCE : The species is common in the Craie d'Obourg, especially at
Harmignies.
Echinocorys conicus
AGASSIZ (Ananchytes).
Echinocorys conicus LAMBERT, 1903, Etude monog. sur le genre Echinocorys. (Mem. Mus.
roy. d'Hist. nat. de Belg., n° 8 [in vol. 2], p. 66, pi. 4, figs. 1-2.)
Tall conical form, with inflated sides, swollen base and a blunt, very weakly
carinate posterior.
The inflated appearance of the sides extends very high, and
FIG. 15 a-c. — Echinocorys conicus. (a) contour (b) longitudinal profile (c) transverse
profile of a specimen from the Craie d'Obourg at Harmignies, figured specimen Musée
d'Histoire Naturelle, Brussels (I. G. 6435). Same specimen figured by Lambert.
the upper surface of the test in the region of the apex narrows to a point rather
abruptly. The swollen base and rounded borders are more extreme than in any
of the near related forms. Peristome a short broad transverse oval; periproct a
narrow longitudinal oval pointed at the ends.
This tall conical species is first represented in the Craie de Triviere by
individuals much larger than ordinarily encountered in the Craie d'Obourg,
with the upper surface in the region of the apex less narrow and less attenuated.
The type from the Craie de Triviere seems to retain some of the characters of
an ancestral form and shows a possible connection with E. gravest. This Craie