702 PROFESSOR A. C. SEWARD ON 



may be compared also with segments of the narrow fronds recently figured by Salfeld 

 from the Lias of N.W. Germany as Otozamites Mandelslohi Kurr. # 



Conclusion. 



The Kimeridgian age of the beds from which the plants of the Culgower flora were 

 obtained has been determined by Professor Judd and by Mr H. B. Woodward from 

 evidence other than palgeobotanical : Mr Woodward considers that the Portlandian 

 series may be represented in the uppermost strata.t The composition of the flora is 

 consistent with the conclusions based on stratigraphical and palseozoological grounds. 



It is generally agreed that the differences between Wealden floras and those from 

 different horizons in the Jurassic system are comparatively small. It may be said 

 without exaggeration, that from the Rhsetic and Liassic periods to the end of the 

 Jurassic period, including the Wealden, the vegetation of Europe experienced no very 

 striking or fundamental change. Many species died out and not a few new types made 

 their appearance during this phase of geological history, but, so far as we know, there 

 was nothing which can reasonably be spoken of as a revolution in the plant- world from 

 the period immediately preceding the beginning of the Jurassic period up to the time 

 immediately following the close of that era. A comparison of such a flora as that 

 described by Schenk from the Rhsetic strata of Franconia with the Wealden floras of 

 England and Northern Germany demonstrates a general agreement, which stands out 

 above the many differences as regards individual elements in these widely separated 

 floras. Similarly, the composition of such Lower Oolitic floras as those from the 

 Yorkshire coast and the plant-beds of Siberia conforms in general terms to that of 

 Rhsetic and Wealden floras. The bearing of this comparison on the Culgower flora is 

 that we should not expect to find an assemblage of plants differing both from older 

 Jurassic types and from the constituents of Wealden floras. Several genera of plants 

 which range from Rhsetic to Wealden floras have been described under different 

 specific names, in some cases as a concession to difference in age rather than as an 

 indication of the existence of well-defined or constant specific characters. 



In the Culgower flora there are certain species which are characteristic of Wealden 

 floras, e.g. Hausmannia dichotoma, Gleichenites cycadina, Baiera Brauniana, Elatides 

 curvifolia, Laccopteris Dunheri. These species, as I have pointed out in the 

 descriptive part of the paper, can all be closely matched with Jurassic types, and in 

 some cases, e.g. Laccopteris, Gleichenites, and Baiera, with Liassic or Rhsetic species. 

 Matonidium Goepperti, not to mention others, is an example of a species common to 

 Middle Jurassic and Wealden floras. In a considerable number of the Culgower plants 

 we have species which are widely distributed in Middle Jurassic floras, e.g. Coniopteris 

 hymenophylloides, Cladophlebis denticulata, Todites Williamsoni, etc. Finally, the 

 species Nilssonia brevis and Tliinnfeldia rhomboidalis are Rhsetic types, the latter 

 species being recorded also from Liassic rocks in England and elsewhere. 



* Salkeld (07), pi. xvi. t See ante, p. 646. 



