88 
ORIGIN OF LIFE IN AMERICA 
California quite a peculiar yellow-billed magpie has arisen, 
which is sometimes distinguished by the name of Pica nutalli. 
It is not at all evident that the ancestors of these American 
magpies entered America by way of Alaska, and yet if mag¬ 
pies had originated in America there would probably be many 
species there ; at any rate, they would inhabit the whole of the 
continent, and perhaps central America as well. Being con¬ 
fined to the west, and differing but slightly from Old-World 
forms, their origin points to Asia. At the same time the fact 
that the American magpie is more like the European form 
than the Asiatic one is a feature which cannot be lost sight 
of. Dr. Diederich discusses the problem whether the 
American magpies arrived in America before or after the 
Glacial Epoch. In spite of the fact that magpies in America 
are entirely migratory and have lived on the continent suffi¬ 
ciently long to develop the peculiar Californian race just 
referred to, Dr. Diederich * inclines to the belief that they 
entered the New World in post-Glacial times. Without any 
fossil or other evidence to guide us, it is difficult to express 
an opinion on this subject. But it seems to me that the 
magpie should be placed into one group with a good many 
other forms of animal life which reached North America long 
before that event, as I shall more fully describe in one of 
the subsequent chapters. 
Dr. Gill, as I mentioned above (p. 83), expressed the 
opinion that the occurrence of Scaphirhynchus in Asia pointed 
in favour of an older land connection between that continent 
and North America. The fish known in America as the 
shovel-nosed sturgeon (Scaphirhynchus platyrhynchus) is 
abundant in the river system of the Mississippi to which it 
is confined. It is now known that its nearest relatives are 
two species inhabiting central Asia which arepoi longer classed 
with Scaphirhynchus, but are placed into the distinct genus 
Kessleria. All these ganoid fishes belong to a very ancient 
group, most of which are extinct. The skeleton of the 
ganoids is generally cartilaginous, and they retain many 
other archaic characters in their anatomical structure. 
Another example is the paddle-fish (Polyodon spathula). It 
Diederich, F., “ Yerbreitung der Elstern,” p. 51. 
