ECIIINOID GENUS ECHINOCOIÎYS

GENUS ECHINOCORYS IN THE SENONIAN OF BELGIUM 5
The conclusions set forth here, if inaccurate are not so due to lack of material
or lack of cooperation from the various persons in charge of Belgian collections.
The writer has handled and examined in varying detail every specimen
made available to him in the collections mentionned above. And in so far as
they were physically able to do so, all the curators have placed at his disposal all
their material.
Acknowledgements.
The writer wishes to express his first and most hearty thanks to Dr. Victor
Van Straelen, Director of the Musée royal d'Histoire naturelle de Belgique, and
to Professor Armand Benier, Chief of the Belgian Geological Service, who first,
during the summer of 1933, interested him in coming to Belgium. They have
assisted, advised and encouraged during the process of the work in Belgium.
Dr. Maxime Glibert, in charge of the Mesozoic and Tertiary collections of the
Musée, has assisted and cooperated in all respects and to him I wish to express
my special thanks..
At Liege, the writer has been assisted primarily by his friend and colleague,
Dr. Paul Macar. Professors Fourmarier and Fraipont have kindly given their
permission for the use of museum and private material. At Mons, Professor
bene Marlière has assisted in every way in making material available and in
discussions. At Louvain, assistance has been rendered by M. l'abbé Demanct,
Professor at the University of Louvain and by the R. P. Remade Rome, conservateur
du Musée paléontologique de l'Université de Louvain.
I wish to express my gratitude to the C. R. B. Educational Foundation, which
has, by granting me a fellowship, made possible this year, as « Collaborateur
étranger°.» at the Musée royal d'Histoire naturelle de Belgique.
Characters of value in separating species and varieties of
Echinocorys.
The basis for the establishment of a species should be a reasonable one and
morphological rather than stratigraphical. Since cchinoids are subject to considerable
variation, in view of many preserved details, many species (as well as
varieties) exist whose differences are unreasonably slight. And often the stratigraphie
position, if different from that of the type, has played a large part in
the separation of forms when they should doubtless have been included as reprcntatives
of existing species with a long range.
In regard to the genus Echinocorys, its variety and overlapping of characters
in the groups forces one to certain artificial distinctions at times. But on the
whole, Uiey are grouped here on the basis of natural morphological differences.
Oftentimes these differences are such that they are little accentuated in the transi-