and size with the age of the animal, so during the history of the 
Tertiary deer has there been a similar development, from the lower 
Miocene forms, whose horns were without antlers, to those of the 
middle and upper Miocene, when they became more complex, until 
their greatest development is reached in the Cervus Setlgwickii of 
the Cromer beds. 
Prof, lloyd Dawkins shows that a similar development of horns 
took place among the Bovidiv. In the Italian Pliocene t here were 
hornless oxen, while the Pleistocene bisons and Uri were 
distinguished by the size of their horns. He suggests that the 
polled cattle produced by domestication, which modification was 
effected by careful selection in about 50 years, furnish us with an 
interesting example of a reversion to an ancestral type. 
The immense collection of mammalian remains which have 
recently been collected by Professor Marsh from tin* American Tertiary 
deposits of the Rocky Mountains, and which it is said will take a 
life time completely to investigate and describe, are likely to afford 
far more important evidence in favour of the derivative hypothesis 
even than that which European palaeontology has given us. 
Sufficient has been already gathered from these fossils to show that 
the pedigree of the horse is by no means an isolated one, but as I 
have already so largely trespassed on your patience, I can only refer 
you to an address delivered by Professor Marsh to the American 
Association for the advancement of Science, in 1877, on the 
“ Introduction and Succession of Vertebrate Life in America,” a 
summary of which appeared in ‘ Mature,’ vol. xvi., p. 418, which 
will well repay careful study. One interesting fact I may perhaps 
quote. Professor Marsh says that all the earliest known Tertiary 
mammals had very small brains, in some cases approaching in size and 
form to that of reptiles. There was a gradual increase in size of this 
organ during the Tertiary era, especially in the cerebral hemispheres, 
or higher portion of the brain, which has also become in some groups 
more convoluted, and thus increased in quality as well as in quantity. 
When wo reach the Pliocene period, we find ourselves among 
mammalian forms which are so closely related to living animals, 
that they assuredly offer no obstacle in the way of our belief in the 
