ECIIINOID GENUS ECHINOCOIÎYS

GENUS ECHINOCORYS IN THE SENONIAN OF BELGIUM 19
Echinocorys subglobosus var. fonticola
ARNAUD.
Echinocorys fonticola ARNAUD, 1897, Bull. S. G. de P. 3 ser., vol. 25, p. 680.
RD
Echinocorys gibbus var. fonticola LAMBERT, 1903, Étude monog. sur le genre Echinocorys.
(Mém. Mus. roy. d'Hist. nat. de Belg., n° 8 [in vol. 2], p. 63, pi. 3, figs. 3-4.)
A small group of individuals occur in the Craie d'Obourg in Belgium which
are exactly like Echinocorys fonticola Arnaud as described and figured by Lambert.
But these individuals are not sufficiently common or different to be any
I hing but a variety and a careful comparison shows them most closely related to
E. subglobosus and not E. gibbus. They have similarities with E. ovatus also
but they even yet retain a superficial resemblance to E. marginatus which brings
them nearer to subglobosus than the later ovatus. They represent a small group
of individuals whose characters are somewhat intermediate between the largest
type E. marginatus and E. subglobosus.
The form of the test is more evenly rotund in appearance than subglobosus,
the apex is evenly rounded or flattened, commonly not at all abruptly elevated
as in subglobosus. The posterior slope is more declivitous than in subglobosus
and there is sometimes developed a posterior carina like the Obourg marginatus.
Other characters remain the same as in E. subglobosus.
OCCURRENCE : This species has been found in the Craie d'Obourg at Harmignies,
is represented by only a few forms and is relatively insignificant except as
an interesting combination of E. marginatus and E. subglobosus characters as
developed in the Craie d'Obourg.
Echinocorys ovatus LESKE (Echinorytes).
Echinocorys ovatus LAMBERT, 1903, Etude monog. sur le genre Echinocorys. (Mem. Mus.
roy. d'Hist nat. de Belg., n° 8 [in vol. 2], p. 69, pi. 4, figs. 6-7.)
This gigantic form fairly common in the Craie d'Obourg of Belgium cannot
easily be otherwise interpreted than as coming directly from E.
The test is consistently large, high and at times, as in Lambert's
subglobosus.
figured
specimen, almost pointed in the region of the apex but gradually so, not abrupt
as in subglobosus. The subglobosity inherited from E. subglobosus persists but
is less conspicuous, due to considerable elongation of the test and the common
development of a prominent posterior carina.
The base is flat, the anterior
border almost straight with very little retraction, almost none in the majority
of individuals.
The peristome is very large, transversely oval and wide anteriorly-posteriorly.
The periproct is oval to round located on the lower surface but is near-marginal
in position. Ambulacra are large, long and prominent as in E. subglobosus.