470 TRANSACTIONS OF SECTION C. 
impressed by the many points of similarity existing between the Millstone Grit 
and the Torridon Sandstone, and is disposed to think that areas of similar 
rock types were laid under contribution for each. 
8. Notes on the Volcanic Rocks and their Associated Sedimenis of the 
Forfarshire Coast between the Red Head and Montrose. By 
ALBERT JOWETT. 
TUESDAY, SEPTEMBER 10. 
The following Papers and Reports were read :— 
1. The Fossil Flora of the Pettycur Limestone in relation to Botanical 
Evolution. By W. T. Gorvon, M.A., B.A., DSc. 
The oldest flora of which we have any considerable knowledge is that repre- 
sented in Upper Devonian rocks, but the plants obtained from Lower Carboni- 
ferous strata do not differ markedly from the Devonian types and so may be 
included in the Devonian flora. Examples of petrified plants of Lower Carboni- 
ferous 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 frag- 
ments 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 organisation 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 specialised than that represented in Upper Carboni- 
ferous strata. 
As the horizon of the Pettycur rocks is rather high in the Calciferous Sand- 
stone 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 discovered. For example, we find 
several genera belonging to one order, or several species to the one genus, and 
in such cases one form is more generalised in structure than the others, while the 
less generalised forms appear to be more closely allied to Upper Carboniferous 
types. 
Among the Lepidodendra, for instance, Lepidodendron Pettycurense, Kid- 
ston, 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 Veltheimianum, 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 may be shown. The lowest member among the Upper Carboni- 
ferous Lepidodendra has a mixed pith, and hence we conclude that the Pettycur 
plants show iess specialisation than those of a later date, though the organisa- 
tion 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 discovered—Cheirostrobus 
pettycurensis, Scott—was recorded from this locality. Certain characteristics 
common to several groups are combined in the cone, which is thus both complex 
and generalised. 
In the megaspore of Lepidodendron Veltheimianum, Sternb., the archegonium 
has been recorded, and it does not differ from that of the living Selaginella or 
Lsoétes. 
To sum up, then, the flora represented in the Pettycur Limestone appears, 
on the whole, to contain more generalised and simpler types than occur in the 
Coal Measure and later strata, and these types may be arranged in order so as to 
suggest certain possible lines of evolution. 
