242 
ELEMENTS OF GEOLOGY. 
p. 262), Ag., and other fish, some of them common to the 
Middle Eocene strata. 
Kleyn Spmoen beds. —The succession of the Lower Miocene 
strata of Belgium can be best studied in the environs of 
Kleyn Spawen, a village situated about seven miles \vest of 
Maestricht, in the old province of Limburg in Belgium. In 
that region, about 200 species of testacea, marine and fresh¬ 
water, have been obtained, with many foraminifera and re¬ 
mains of fish. In none of the Belgian Lower Miocene strata 
could I find any nummulites; and M. d’Archiac had pre¬ 
viously observed that these foraminifera characterize his 
“ Lower Tertiary Series,” as contrasted with the Middle, and 
they therefore serve as a good test of age between Eocene 
and Miocene, at least in Belgium and the North of France.* 
Between the Bolderberg beds and the Rupelian clay there is 
a great gap in Belgium, which seems, according to M. Bey- 
rich, to be filled up in the North of Germany by what he 
calls the Sternberg beds, and w^hich, had Dumont found them 
in Belgium, he might probably have termed Upper Rupelian. 
Lower Miocene of Germany. —Rupelian Clay of Ilermsdorf 
near Berlin. —Professor Beyrich has described a mass of clay, 
used for making tiles, within seven miles of the gates of Ber¬ 
lin, near the village of Hermsdorf, rising up from beneath 
the sands with which that country is chiefiy overspread. 
This clay is more than forty feet thick, of a dark bluish- 
gray color, and, like that of Rupelmonde, contains septaria. 
Among other shells, the Leda JDeshayesiana^ before mention¬ 
ed (Fig. 156), abounds, together with many species of Bleu- 
rotoma^ Vbluta, etc., a certain proportion of the fossils being 
identical in species with those of Rupelmonde. 
Mayence Basin. —An elaborate description has been pub¬ 
lished by Dr. F. Sandberger of the Mayence tertiary area, 
which occupies a tract from five to twelve miles in breadth, 
extending fbr a great distance along the left bank of the 
Rhine from Mayence to the neighborhood of Manheim, and 
which is also found to the east, north, and south-west of 
Frankfort. M. de Koninck, of Liege, first pointed out to me 
that the purely marine portion of the deposit contained many 
species of shells common to the Kleyn Spawen beds, and to 
the clay of Rupelmonde, near Antwerp. Among these he 
mentioned Cassidaria depressa.^ Tritonium argutimi^ Bran- 
der {T. flandricumfD^ Koninck), Tornatella simidata.^ Apor^ 
rhais Sowerbyi.^ Leda Deshay esiana (Fig. \hC).,Corbidapisimi.^ 
(Fig. 158, p. 245), and others. 
Lower Miocene Beds of Croatia. —The Brown Coal of Rada- 
* E’Archiac, Monogr., pp. 79, 100. 
