THE MIOCENE PERIOD. 305 
dence of the existence in Europe at this period of examples of 
the orders of the Gnawing Mammals (Aodentia), the Insect- 
Fig. 233.—Portion of the skeleton of Vesfertilio Parisiensis. Eocene Tertiary, France. 
eating Mammals (/msectivora), and the Monkeys (Quadru- 
mana).* 
CART Tike (2G Xe 
LITLE MIOCENE PERIOD: 
The Miocene rocks comprise those Tertiary deposits which 
contain less than about 35 per cent of existing species of shells 
(Mollusca), and more than 5 per cent—or those deposits in 
which the proportion of living shells is less than of extinct 
species. They are divisible into a Lower Miocene (Oligocene) 
and an Upper Miocene series. 
In Britain, the Miocene rocks are very poorly developed, 
one of their leading developments being at Bovey Tracy in 
Devonshire, where there occur sands, clays, and beds of lignite 
* A short list of the more important works relating to the Eocene 
rocks and fossils will be given after all the Tertiary deposits have been 
treated of. 
U 
