TRANSACTIOxVS OF SECTION K. 



841 



A comparison of fossil and recent conifers is rendered difficult by the lack of 

 satisfactory evidence as to the systematic position of many of the commoner types 

 met with in Mesozoic rocks. There are, however, certain broad generalisations 

 which we are justified in making; such genera as the Pines, Firs, Larches, and 

 other members of the Abietinepe appear to have occupied a subordinate position 

 during the Triassic and Jurassic eras ; it is among the relics of Wealden and 

 Lower Cretaceous floras that cones and vegetative shoots like those of recent Pines 

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

 Conifers to which such artificial designations as Pagiophyllinn, BrcicJiyphrillum, 

 and others have been assigned, which cannot be referred with certainty to a par- 

 ticular section of the Conifers ; these forms, however, exhibit distinct indications 

 of a close relationship with the Araucariese, represented in modern floras by 

 Araucaria and Agathis. The abundance of cones in Jurassic strata showing the 

 characteristic features of those of recent species of Araucaria aflPords trustworthy 

 evidence as to the antiquitj' of the Araucarieae and demonstrates their wide geo- 

 graphical distribution during the Mesozoic era. At the present day the Arauca- 

 rie;B comprise the two genera Araucaria and Agathis, the former including ten 

 species occurring in South America and Australia, and the latter comprising four 

 species which flourish in the M.ilay Archipelago, New Zealand, the Philippines, 

 North-East Australia, and .elsewhere. Sir William Thiselton-Dyer pointed out, 

 in a lecture on plant-distribution, delivered in 1878, that the genus Araucaria 

 appears to have been extinct in a wild state north of the Equator since the Jurassic 

 epoch. Additional confirmation of the important status of this section of the 

 Coniferse is afforded by the abundance of petrified wood exhibiting Araucarian 

 features, in both Jurassic and Wealden rocks. There is good reason to believe 

 that the well-known Whitby jet was formed by the alteration of blocks of Arau- 

 carian wood drifted from forest-clad slopes overlooking a Jurassic estuary that 

 occupied the site of the moors and headlands of North-East Yorkshire. Among 

 familiar Jurassic genera, mention must be made of the genus Brachyphyllum, 

 including species referred by some authors to Athrotaxites, represented by frag- 

 ments of leafy twigs and branches bearing a striking resemblance to those of the 

 isolated Tasmanian genus Athrotaxis. Omitting further reference to the various 

 indications aflbrded by a study of Mesozoic Conifers as to the former extension of 

 many of the more isolated recent types, we may present in a tabular form an 

 epitome of the past and present range of the Araucariese : — • 



Geographical Distribution of Past and Present AEAtrcAEiEJE. 



