LINNEAN SOCIETY OP LONDOK. 6$ 



DlSCUSSIOX. 



Dr. D. IT. tScoTT congratulated Mr. Parkin on Iiis pa|)er, wliicli 

 in addition to its great scientific interest, was an act of loyalty to 

 the iiieiiiory of an old friend, whose loss we all lamented. 



The speaker began by sliowing slides of the famous Hermosa 

 Cycud (C'l/cculeoidea Dartoni),o\ie of the finest fossil plants known. 

 On the part of tlie stem preserved, no less than 50i) ripe fruits 

 were present, indicating that these plants may have fruited once 

 for all and then died down, like some ]ialms and bamboos at the 

 present day. 



Dr. Wieland had pointed out that the Bennettitean Cycads 

 were '' the stereotyped terminal forms of a side-branch from a 

 great plastic and dominant precursor race." He added that the 

 former were "exceptional to the point of abnormality." 



Thus Wieland, to whom, more than any other individual, our 

 present knowledge of the Ijeunettiteans was due, liad himself 

 warned us not to over-estimate their importance. 



What then, was the " great plastic and dominant precursor 

 race," which formed the main stock of JNTesozoic Cycads V It was 

 represented by the Williamsonian Tribe, a varied and extensive 

 family, which included, broadly speaking, the more ancient 

 members of the Cycadeoid class. 



Lantern-slides were shown, illustrating the flowers and vege- 

 tative parts of WiUiamsonia itself, of Mr. Hamshaw Thomas's 

 new genus WilliamsonieUa, and of Nathorst's Wiehmdiella. The 

 latter genera, especially, departed widely from the Cycad type, as 

 shown by their slender, much-branched stems and simpler leaves. 

 If the origin of Angiosperms was to be sought among the ancient 

 Cycadophyres, it was probably with the Williamsonian Tribe that 

 the closer relation existed. 



In these days one had learnt greater caution in speculations on 

 ])hylogeny. Mr. Parkin hnd stated his case with becoming mode- 

 ration and had shown that the derivation of the Flowering Plants 

 from the great Cycadeoid plexus of the Mesozoic Age, was at 

 least a tenable hypothesis. 



Mr. H. H.virsHAW THo:\rAS (visitor) contended that all evolu- 

 tionary theories nuist be concordant with Pala^obotaiiical facts. 

 Kecent work shows that in the JNIiddle Jurassic a group of plants 

 existed as Angiosperms, though considerably different from those 

 now existing. In some of the Jurassic Bennettitales are a few 

 characters similar to those occurring in Angiosperms of to-day, 

 but differing mai'kedly in the structure of the gyno'cium. 



In the same bed as Willi amsoniella, the speaker had unearthed 

 female inflorescences and fruits of two genera which are un- 

 doubtedly Angios])erms, though their microsporangia or male 

 flowers have not been found. These genera are Orislhorpia and 

 Caytonia and were dis])layed in a series of lantern-slides : they 

 probably bore leaves of the type long known as SfKienoptens, 



LI>'X. SOC. PROCEKDIXGS, — SESSION 1922 2l>. f 



