468 Notices of Memoirs — Fossil. Flora, Pettycur, Fife. 



and Paris for comparison with standard collections, resulting in identi- 

 fication of a large proportion of well-known European types in the 

 ' Fern Ledges ' flora, all Carboniferous and mostly typical of Westphalian 

 division in Coal-measures. Note the value of fossil plants, as the 

 Carboniferous age of the beds was recognized by Geinitz in 1866 from 

 a single specimen off a fern leaf. The author did the work for the 

 Canadian Geological Survey, to the kindness of whose Director is due 

 the permission to give this resume of the results. 



VI. — The Fossil Flora of the Pettycue Limestone in relation to 

 Botanical Evolution.' By W. T. Gordon, M.A., B.A., D.Sc. 



THE oldest flora of which we have considerable knowledge is that 

 represented in Upper Devonian rocks, but the plants obtained from 

 Lower, Carboniferous strata do not differ markedly from the Devonian 

 types, and so may be included in the Devonian flora. Examples of 

 petrified plants of Lower Carboniferous age have been recorded from 

 several localities in Scotland, but they are nowhere so abundant as at 

 Pettycur, near Kinghorn, Fife. The flora of the Pettycur Limestone, 

 then, has a double interest ; the remains constitute fragments of the 

 oldest known flora, and, as they are petrified, the internal structure of 

 these plants may be studied. 



Although the Devonian flora is very distinct from that of the 

 succeeding Permo-Carboniferous epoch, yet the organization does not 

 indicate that the plants were primitive. Indeed, all one can say is 

 that the assemblage, as a whole, appears to be less highly specialized 

 than that represented in Upper Carboniferous strata. 



As the horizon of the Pettycur rocks is rather high in the Oalciferous 

 Sandstone Series, we would expect to find some species whose structure 

 indicated a transition between Devonian and Upper Carboniferous 

 forms. In some cases I believe that such specimens have been dis- 

 covered. For example, we find several genera belonging to one order, 

 or several species to the one genus, and in such case? one form is more 

 generalized in structure than the others, while the less generalized 

 forms appear to be more closely allied to Upper Carboniferous types. 



Among the Lepldodendra, for instance, Lepidodendron Petfyciirense, 

 Kidston, has a perfectly solid central axis ; the xylem cylinder in 

 Lepidophloios Scottii, Gordon, is occasionally solid in places, but at 

 other parts of the same specimen a mixed pith, consisting of parenchyma 

 and short tracheides, may be noted. Lepidodendron V eltheimianum, 

 Sternb., on the other hand, has a well-marked parenchymatous pith 

 containing no tracheides. A line of development is thus suggested by 

 this series, and when we turn to the Coal-measure flora a parallel 

 series maj- be shown. The lowest member among the Upper Carboni- 

 ferous Lepidodendra has a mixed pith, and hence we conclude tliat the 

 Pettycur plants show less specialization than those of a later date, 

 though the organization is similar in each case. Such parallel series may 

 also be demonstrated in other groups, particularly among the ferns and 

 Pteridosperms. 



The various reproductive members met with at Pettycur also exhibit 

 certain peculiarities. The most complex cryptogamic cone yet dis- 

 covered — Cheirosti-obus Pettycurensis, Scott — was recorded from this 

 locality. Certain characteristics common to several groups are combined 

 in the cone, which is thus both complex and generalized. 



In the megaspore of Lepidodendron V eltheimianum, Sternb., the 

 archegonium has been recorded, and it does not differ from that of the 

 living Selaginella or Isoetes. 



' Abstract of paper read before the British Association, Section C (Geology), 

 Dundee, September, 1912. 



