88 THE LESSON OF EVOLUTION 



In the Cretaceous period nearly half of the 

 Dicotyledons belonged to the Apetaloe, such as 

 willows, poplars, oaks, walnuts, figs, &c. About half 

 belonged to the Polypetalae; while the Gamopetalse 

 formed but five per cent, of the whole. . The heaths, 

 clovers, rhododendrons, myrtles, olives, and Composite 

 appear in the Oligocene ; the azaleas and convolvulus 

 in the Miocene ; but the Gamopetalse were still in a 

 minority, and did not attain their present position 

 until recent times. A table will show this better 

 than any description. 



Apetalse. Polypetalae. Gamopetalae. 



Cretaceous 45 p.c. 50 p.c. 5 p.c. of the flora. 

 Miocene 37 p.c. 48 p.c. 15 p.c. 

 Eecent 14 p.c. 50 p.c. 46 p.c. 



The introduction of herbaceous grasses must have 

 materially affected mammalian life. According to Mr 

 J. Starkie Gardner 1 grasses are first known in the 

 upper Cretaceous of Europe, North America, and 

 Greenland. The specimens are very fragmentary ; 

 but all appear to have been arborescent, like the 

 bamboos of the present day. None are known with 

 certainty from the lower Eocene, a few appear in the 

 upper Eocene ; but in the Oligocene and Miocene 

 herbaceous grasses are abundant. It also appears 

 that none of the Eocene mammals have their teeth 

 specially adapted for eating grasses ; but that they 

 gradually became modified in this direction during 

 the Miocene. 



The first known butterflies and bees are from the 



1 Proceedings of the Geologists' Association of London, 1886, p. 433. 



