56 PEOCEEDINGS OF THE 



lY. 



The Evolution of Gymnosperms : The Position and Ancestiy of 

 the Araucariese. By A. C. Sewaed, F.E.S., F.L.S. 



[Read loth March, 1906.] 



The genera Araucaria and Agailiis may be regarded as surviving 

 members of an ancient group of Gymnosperms distinguished by 

 several well-marked characters from other Coniferales. During 

 the Mesozoie era the Araucarieae were widely distributed and 

 played a prominent part in the Northern floras ; they are now 

 confined to comparatively restricted areas in the Southern hemi- 

 sphere. Our object is to enquire into the evidence on which the 

 statement as to the antiquity of the Araucarieae is based, and to 

 ascertain whether the records of the rocks lend support to a view 

 expressed by some botanists that they represent the oldest section 

 of the Coniferales. A further question suggested by the exami- 

 nation of palaeontological data, is the possession by Agatlds and 

 Araucaria of characters which may be designated pi'imiti\e. 



In view of the widely accepted conclusion that Cycads and 

 Ferns Avere descended from common ancestors, it is important 

 to consider whether the contention that Conifers as well as Cycads 

 are derived from a Filicinean stock is supported by satisfactory 

 evidence. While accepting Cycads as descendants of Eilicinean 

 ancestors, the Author is led to the conclusion that Conifers, or at 

 least the Araucariej©, should be referred to a Lycopodiaceous 

 origin. 



The following headings may serve to suggest some of the 

 questions to be dealt with in discussing the origin ot the 

 Araucai'iese : — 



i. The W'idespead occurrence of Mesozoie fossils referred to 

 the Araucarieae. 



ii. Features in which Agathis and Araucaria diff'er from other 

 members of the Coniferales : the isolated character of 

 the Araucarieae and the primitive nature of some of 

 their peculiarities. 



iii. Examination of the evidence adduced in favour of in- 

 cluding Conifers with Cycads as descendants of Eilicinean. 

 ancestors. 



iv. Comparison of the vegetative and reproductive shoots of 

 the Araucarieae with those of recent and fossil Lycopods 

 from the point of view of a close relationship between 

 the two pbyla. 



