HERTFORDSHIRE NATURAL HISTORY SOCIETY. 
XXIX 
which originally commemorated the victories of Philip at Olympia, 
the charioteer has grown wings, but the body, fore-arms, and whip 
have become represented by a series of dots or pellets, the wheel of 
the chariot only at times survives, and the two horses have become 
amalgamated, though the legs are often bifid in remembrance 
of the original duality of the animal. All traces of the name 
OlAinnOY have disappeared. 
Starting with this British prototype, the next question is as to 
the laws which regulate its farther modifications, and how they are 
allied to those of natural selection. It is hardly necessary to enter 
at any length upon the theory of evolution with which the name of 
Darwin will ever be associated. It is, however, desirable to give a 
brief summary of some of its principal features. 
In successive generations of animals and plants, though the 
offspring as a rule absolutely resembles the parents, there is always 
a tendency to variation, so that forms in some degree varying from 
the parent form are from time to time liable to make their ap¬ 
pearance. 
If in the struggle for existence these new varieties possess any 
advantage over the forms already in being, they are likely to be 
perpetuated, though for a length of time there is a liability in their 
progeny to revert in the direction of the earlier form. 
Even long after some organ, owing to modifications in the mode 
of life, has ceased to be of service to the organism, it frequently 
survives in an atrophied form. 
Moreover, the degree in which a variety or modification is 
advantageous, and therefore likely to be perpetuated, is to a great 
extent dependent on external conditions, the changes in which afford 
opportunities for new forms to prove their utility. 
No doubt this theory of descent with variation holds good with 
regard to most of the appliances of man ; but it is more especially 
with regard to the changes in the types of coins, and in other 
ornamental devices among people in a low stage of culture, that we 
can trace laws somewhat analogous to those of natural selection. 
To the evolution of culture General Pitt-Bivers has devoted especial 
attention, and the present discourse is restricted to one special class 
of coins, though similar results to those which are found in Britain 
might be observed in the early coinage of some other countries. 
The necessities of the case with regard to coins are : 1. That the 
successive issues or generations of coins should resemble each other 
sufficiently to pass current together; but, 2. Art being imperfect, 
there must have been more or less important variations and modifica¬ 
tions in the successive dies which were engraved. This tendency 
to variation was increased by the necessity of the dies being rather 
larger in diameter than the coins which were struck from them, so 
that the new dies were often copied from coins not showing the 
whole of the device. They were also frequently copied from coins 
worn by circulation, and in many instances the external influence 
of the introduction of foreign artists made itself powerfully felt. 
3. When not disturbed by this foreign element, the requirements 
