PALEOBOTANICAL EVIDENCE OZ'6 



species), Austria-Hungary (22 genera, 29 species), and Eurasia (18 

 genera, 23 species). These floras are made up mainly of ferns, cycads, 

 and conifers, no dicotyledons being known to be present. 



The Aptian is believed to be represented in North America by the 

 Glen Eose limestone of Texas, with 16 genera and 25 nominal species, 

 of which 8 are cycads, 11 conifers, and 1 fern, and by the Lakota sand- 

 stone of the Black Hills region, which includes 21 genera and 59 species, 

 there being 13 ferns, 33 cycads, and 8 conifers; neither includes dicoty- 

 ledons. 



In Europe the Aptian is known from France (2 genera, 2 species), 

 Germany (9 genera, 12 species), Italy (13 species, 1 genus of cycads), 

 and Portugal (21 genera, 25 species), the cycads predominating and 

 angiosperms absent. 



The uppermost portion of the Lower Cretaceous, the Albian of Europe, 

 witnessed — at least in extenso — the formal establishment of the since 

 dominant angiospermous types of vegetation and the beginning of the 

 decline of ferns, cycads, and conifers. The Patapsco formation of 

 Maryland and Virginia has afforded a flora of not less than 60 species, 

 of which number 25 are undoubted angiosperms. These are so diversi- 

 fied in type and so highly organized as to suggest strongly a long pre- 

 vious period of development, but we do not yet know when or just where 

 the evolution took place. They began immediately the conquest of the 

 earth, and the Fuson formation of the Black Hills region, though still 

 having a preponderance of ferns, cycads, and conifers, included some 

 half dozen angiosperms. 



In beds of Albian age in Portugal there is a considerable flora (36 

 genera, 66 species) which embraces 20 ferns, 6 cycads, 18 gymnosperms, 

 and 22 angiosperms, a number of which are identical with species in the 

 Patapsco formation. The Upper Albion of Portugal contains a flora 

 of 15 genera and 26 species, but has no ferns or cycads and but a single 

 conifer, the remainder being all angiosperms. Small floras of Albian 

 age are known from England (3 genera, 8 species) and France (17 

 genera, 35 species), but they are without kno"\vn angiosperms. 



As regards the climatic conditions that may fairly be presumed to 

 have obtained during the upper part of the Lower Cretaceous, I can 

 see no reason for supposing that it was greatly different from that alreadv- 

 indicated for the lowest Cretaceous, namely, equability, abundant moist- 

 ure well distributed throughout the year, and a temperature that was 

 at least warm temperate. 



