Earthworms and Their AlliesBeddard, Frank E. (Frank Evers)
Science
Earthworms and Their Allies
Beddard, Frank E. (Frank Evers)
Earthworms
From this brief statement of facts some inferences of interest can
be drawn. It is in the first place plain that every part of the
world except the extreme north and south has a considerable fauna of
earthworms. The one exception would appear to be the northern part
of the North American continent. Here we meet with members of the
family Lumbricidae which are however species that are met with in
the Euro-Asiatic province and are thus to be regarded as possibly
later immigrants introduced probably by man. Thus temperature
short of a constantly frozen condition of the ground is not a bar
to the existence of earthworms. Even a freezing of the ground for
lengthy periods is not a complete obstacle to the existence of those
Annelids; for I have myself received examples of Lumbricidae from
the arctic island of Kolguev. Moreover the temperate regions would
seem to be as fully populated in the way of individuals, and even of
species, as are the tropical regions. Indeed as to individuals it
seems that the temperate regions are more fully supplied than much
of the tropics. This however is not quite the object of the present
section to discuss. We are here concerned with the relative frequency
of genera and species. There are according to a recent estimate of
the Rev. H. Friend some forty species recognisable in Great Britain.
And as already has been stated the earthworms of Europe amount to
perhaps 130,--at any rate well over one hundred. In tropical America
there are hardly more. But in the latter case the number of genera is
very greatly in excess of that of Europe. We cannot however say that
an abundance of generic types is quite characteristic of the tropics.
For the Eastern Archipelago, though rich in species, is but poor
in genera, not possessing more than half a dozen or so. And on the
other hand the temperate climate of New Zealand has produced a very
considerable series of genera, much more than those of the islands
of the East and nearly as many as those of, for instance, Central
America and the West Indies.
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