114 EVOLUTION IN THE PAST 



through the agency of birds, or by sea-transport, or by land- 

 connections which no longer exist — it is difficult to say. 

 Having, however, once obtained a footing, the invaders 

 gradually extended their range, being reinforced from time 

 to time by various other emigrants of their class. So success- 

 ful was the progress that in the latter part of the Period 

 fig trees, eucalyptus, oaks, poplars, grasses and other angio- 

 sperms had annexed large districts in Europe. But although 

 conifers were being displaced in many parts of Europe and in 

 America, they still flourished over vast areas on both conti- 

 nents. In addition to the nine points of the law in their 

 favour, the soil in many districts was doubtless more suitable 

 to them than to the new-comers. 



Pahns also were making their appearance. There is little 

 doubt they were descendants of some early forms of cycads. 

 This effort to confront new conditions was another sign of 

 ' the resourcefulness of that Order. 

 INSECTS Hosts of insects must have accompanied the new vegeta- 

 tion, for plants and insects, then as now, were doubtless 

 in many cases dependent on each other — the insects for food, 

 and the plants for the transference of their pollen. Bees, 

 butterflies, and moths are helpful in fertilisation ; but it is 

 impossible to say how far the vegetation was benefited by 

 insects at this time. The evidence of insect-hfe in the 

 Cretaceous is very meagre. Bees had appeared in the 

 Jurassic, but the evidence as to butterfhes at that time is not 

 satisfactory ; nor is there better evidence in the Cre- 

 taceous. There is, however, good reason to think that 

 moths had by this time made their appearance (Tineidce, 

 Tortricidce). 

 MAMMALS Here then were trees, shrubs, and grasses as a table spread 

 for mammals ; but so far as is known these creatures 

 exhibited very little progress over their forerunners (Dryo- 

 lestes, Didelphops, etc.). They all appear to have been of 

 small size ; and no remains of forms of higher rank than 

 marsupials have as yet been discovered. Reptiles stUl held 

 the field. It is, however, extremely probable that in some 

 lands, the strata of which have as yet been very little 

 explored, mammals of higher type had come into being. But 



