Vol. 59.] OCCURRENCE OF DICTYOZAMITES IN ENGLAND. 229 



species as are founded on inadequate evidence, with a view to 

 discover the chief distinguishing features which they exhibit, as 

 compared with the Jurassic vegetation of England, we find very little 

 indication of any hut minor differences. The Bornholm flora is 

 essentially of the same general botanical type as that of Yorkshire, 

 the chief distinguishing features being due to the greater resem- 

 blance, as regards certain types, to such IMiaetic floras as those of 

 Eranconia l and Scania 2 ; but these differences are rather of the 

 nature of the relative representation of particular families, than 

 of a kind that one would expect to find had the vegetation of the 

 two regions flourished under different conditions. Taking the two 

 European floras together, and contrasting them with those of Japan 

 and India, we note the prominence of the Matonineae 3 (Matonidium, 

 Laccopteris) and the Dipteridinae, 4 Dictyo-phyllum and ProtorMpis 5 

 (including species of Hausmannia of Moller), as contrasted with 

 the apparent absence of these families of Eerns in the Eastern floras. 

 Similarly the Ginkgoales 6 are not represented by any species which 

 we can assign with confidence to either Ginkgo or Baiera in the 

 Indian flora. One of the genera recorded from India, and not 

 represented in the floras of Yorkshire or Bornholm, is Cycadites, but 

 the Bajmahal forms of this genus may well be identical with a 

 European species, Cycadites rectangidaris, which occurs in the Liassic 

 strata of England and in the Ilhaetic flora of Eranconia. 



In all the floras Cycadean plants play an important part. With 

 regard to Williamsonia we have proof of its occurrence, in both 

 India and Western Europe, supplied by the presence of reproductive 

 organs ; but the other Cycadophyta common to the different regions 

 are represented almost solely by vegetative fragments. 



A striking agreement, as regards the Eerns represented in the 

 Eastern and Western floras, is clearly brought out in the foregoing 

 lists. The Conifers of India and England agree in including repre- 

 sentatives of Araucarites, but for the rest a comparison as regards 

 family or generic identity is almost impossible in the absence of well- 

 preserved cones. Such vegetative specimens as occur in the four floras 

 appear to be of similar type, and we are justified in the conclusion 

 that there is no evidence of any striking contrast between the Conifers 

 of the East and the West. The character of the vegetation of the 

 world from the Upper Triassic Period to the Wealden seems to have 

 been remarkably uniform and constant in its main features. On a 

 future occasion I hope to discuss in greater detail the distribution 

 and composition of the various floras of Mesozoic type. The marked 

 contrast exhibited by the Palaeozoic vegetation on the one hand, 

 and the Tertiary vegetation (including that of the greater part of 

 the Cretaceous Era) on the other, to that which flourished through 

 the whole Jurassic Era is a striking fact, well worthv of more 

 critical and extensive consideration than it has so far received. 



1 Schenk (67). 2 Nathorst (78) (78 2 ) & (78 3 ) 



3 Seward (99). 4 See also Zeiller (97). 



5 Seward & Dale (01). G Seward & Gowan (00). 



