XX11 IXTEODTJCTION. 



sperms might be deemed appropriate. Many leaf-impressions 

 from deposits somewhat older than the Aptian (e. g. the 

 * Potomac" of America) have been described, but the exact 

 correlation of these deposits with the European beds is still 

 very uncertain. In those beds which are clearly older than 

 Aptian, on the other hand, the records of reputed Dicotyledons, 

 though numerous, are far from securely established (see p. 259). 

 In the Kootanie and Horsetown beds, for instance, which are 

 definitely older than the Aptian, the recorded Angiosperms are 

 very doubtful. Similarly in Europe, the pre-Aptian Angiosperms 

 and pro-Angiosperms of Saporta (1894) cannot be accepted 

 unhesitatingly. 



Nevertheless, it is certain that Angiosperms, to have spread 

 so widely by Aptian times, must have existed either actually 

 or potentially in some pro-angiospermic character, by the 

 Jurassic, possibly even by Triassic times. 



As will be seen in the descriptive part of this work (pp. 260- 

 294), the Aptian stems were woody plants of a highly advanced 

 and differentiated character, and there is nothing in their 

 anatomy to indicate any more clearly their phylogenetic origin 

 than there is in the stems of the still living genera. The origin 

 of the Angiosperms remains the "abominable mystery" Darwin 

 thought it. The solution via the Bennettitales has never 

 commended itself to me, and the existence of such highly 

 differentiated Angiosperms in the strata from which the typical 

 Bennettites Q-ibsoninmts and others were obtained, renders it still 

 more incredible that there should be a Bennettitalean ancestry 

 for the Angiosperms. 



CLIMATE. 



As geologists are at present almost without information 

 regarding the laud-conditions of the Aptian of Northern Europe, 

 they may ask what evidence regarding the climate is given by 

 the plants now described. 



It is evident from their structure that these plants inhabited 

 an ordinary dry, or comparatively high, land. As the fossils 

 had all drifted in sea-water at least some short distance before 

 they were petrified, we cannot be quite sure that they all lived 

 close together. Their states of preservation and the amount of 

 teredo-boring they endured, however, favour the view that they 



