Palaeontologie. 477 



the commoner types met with in Mesozoic rocks. There are, 

 however, certain broad generalisations which we are justified 

 in making; sucii genera as tiie Pines, Firs^ Larches, and other 

 members of the Abletineae appear to have occupied a sub- 

 ordinMte position during the Triassic and Jurassic eras: it is 

 among the relics of Wealden and Lower Cretaceoiis floras that 

 cones and vegetative shoots like those of recent Pines occiir 

 for the first time in a position of importance. There are several 

 Mesozoic Conifers, which cannot be referred with certainty to 

 a particular section of the Coniferae ; these forms, however, 

 exhibit distinct indications of a ciose relationship with the 

 Araucarieae, represented in modern floras by Araiicaria and 

 Agathls. The abundance of cones in Jurassic strata shov.ing 

 the characteristic features of those of recent species of Araiicaria 

 affords trustworthy evidence as to the antiquity of the Arau- 

 carieae and demonstrates their wide geographica! distribution 

 during the Mesozoic era. 



b. Cycads. One of the most striking features of the Meso- 

 zoic Vegetation is the abundance and wide distribution of 

 Cycadean plants. To-day the Cycads or Sago - Palms are 

 represented by ten genera and about eighty species. Before 

 the end of the Palaeozoic era there existed plants bearing 

 pinnate fronds similar to those of recent species of Cycadaceae, 

 and in succeeding ages the group rapidly increased in number 

 and variety tili, in the Jurassic and the early Cretaceous periods^ 

 the Cycads asserted their superiority as the leading type of 

 Vegetation. We are in possession of enough facts to justify the 

 Statement that the majority of Mesozoic Cycads bore repro- 

 ductive Organs which differed in important morphological 

 characters from those of existing forms. The Bennettiteae, 

 originally founded on a petrified stem discovered more than 

 fifty years ago in the Isle of Wight, possessed a thick stem^ 

 clothed with an armour of persistent leaf-bases and bearing a 

 crown of pinnate fronds, as in most modern Cycads; but their 

 flowers, which were borne on lateral shoots, were more highly 

 specialised than those of the true Cycads. While most of the 

 Mesozoic Cycads were no doubt members of the Bemiettiteae, 

 others appear to have possessed reproductive organs like those 

 of recent species. 



c. Ginkgoales. Before leaving the Gymnosperms a word 

 must be said about another section — the Ginkgoales — 

 represented by the Maidenhair-tree of China and Japan. 

 The abundance of fossil leaves, like those of Ginkgo biloba, and 

 of other slightly different forms referred to the genus Baiera, 

 associated not infrequently with remains of male and female 

 flowers, demonstrates the ubiquitous character of the Ginkgoales 

 during the Rhaetic, Jurassic, and Wealden periods. In the 

 Jurassic shales of the Yorkshire Coast, Ginkgo and Baiera 

 leaves occur in plenty, some of them practically identical with 

 those of the existing species. The abundance of fossil 



