Europe was thus permitted. This view is borne out by the fact
that the Miocene plants of Europe are most nearly allied to the
living plants of the eastern or Atlantic seaboard of the United
States, and also by the occurrence of a rich Miocene flora in
Greenland. As regards Greenland, Dr Heer has determined that
the Miocene plants indicate a temperate climate in that country,
with a mean annual temperature at least 30 deg. warmer than it is
at present.

The present limit of trees is the isothermal which gives the
mean temperature of 500 Fahr. in July, or about the parallel of
67 deg. N. latitude. In Miocene times, however, the Limes, Cypresses,
and Plane-trees reach the 79th degree of latitude, and the Pines
and Poplars must have ranged even further north than this.

The _Invertebrate Animals_ of the Miocene period are very numerous,
but they belong for the most part to existing types, and they
can only receive scanty consideration here. The little shells of
_Foraminifera_ are extremely abundant in some beds, the genera
being in many cases such as now flourish abundantly in our seas.
The principal forms belong to the genera _Textularia_ (fig. 237),
_Robulina, Glandulina, Polystomella, Amplistegina_, &c. Corals
are very abundant, in many instances forming regular "reefs;"
but all the more important groups are in existence at the present
day. The Red Coral (_Corallium_), so largely sought after as an
ornamental material, appears for the first time in deposits of
this age. Amongst the _Echinoderms_, we meet with Heart-Urchins
(_Spatangus_), Cake-Urchins (_Scutella_; fig. 238), and various
other forms, the majority of which are closely allied to forms
now in existence.

[Illustration: Fig. 237.--_Textularia Meyeriana_, greatly enlarged.
Miocene Tertiary.]

Numerous Crabs and Lobsters represent the _Crustacea_; but the most
important of the Miocene Articulate Animals are the _Insects_. Of
these, more than thirteen hundred species have been determined by
Dr Heer from the Miocene strata of Switzerland alone. They include
almost all the existing orders of insects, such as numerous and
varied forms of Beetles (_Coleoptera_), Forest-bugs (_Hemiptera_),
Ants (_Hymenoptera_), Flies (_Diptera_), Termites and Dragon-flies
(_Neuroptera_), Grasshoppers (_Orthoptera_), and Butterflies
(_Lepidoptera_). One of the latter, the well-known _Vanessa Pluto_
of the Brown Coals of Croatia, even exhibits the pattern of the
wing, and to som