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I
CHAP. XIX.] KEPTILES. 387
lidse. The Australian has 16, belonging to three families only ;
eleven being Elapidse, and four Pythonidse. The Neotropical has
about 24, belonging to eight families ; ten are Colubridse, six
Pythonidse, and the rest Dipsadidae, Scytalidse, Amblycephalidse,
Elapidse, and Crotalidae.
We find then, that in the Ophidia, the regions adopted in this
work are remarkably distinct ; and that, in the case of the Orien-
tal and Ethiopian, the difference is strongly marked, a very large
number of the genera being confined to each region. It is in-
teresting to observe, that in many cases the affinity seems to be
rather between the West Coast of Africa and the Oriental
region, than between the East Coast and the plains of India;
thus the Homalopsidse—a highly characteristic Oriental family
occur on the West Coast of Africa only ; the Dryiophidse, which
range over the whole Oriental region, only occur in Madagascar
and West Africa in the Ethiopian ; the genus Dipsas is found over
aU the Oriental region and again in West Africa. A cause for this
peculiarity has been suggested in our sketch of the past history
of the Ethiopian region, Vol. I. p. 288. In the Lycodontidse,
which are strictly confined to these two regions, the genera are
aU distinct, and the same is the case with the more widely dis-
tributed Elapidse; and although a few desert forms, such as
EcMs and the Erycidse, are common to Africa and the dry plains
of India, this is evidently due to favourable climatic conditions,
and cannot neutralise the striking differences in the great mass
of the family and generic forms which inhabit the two regions.
The union of Madagascar with the South-western part of the
Oriental region under the appellation Lemuria, finds no support
in the distribution of Ophidia ; which, however, strikingly accords
with the views developed in the Third Part of this work, as to the
great importance and high antiquity of the Euro-Asiatic conti-
nent, as the chief land-centre from which the higher organisms
have spread over the globe.
Fossil Ophidia.—The oldest known remains of Ophidia occur
in the Eocene formation in the Isle of Sheppey ;
—
others are found
in the Miocene (Brown Coal) of Germany, and in some Tertiary
beds in the United States. Most of these appear to have been