286 Palaeontologie. 



Australia, Japan, China, and in the Northern hemisphere, 

 in North America, Greenland, and other Arctic lands, and 

 throughout Europe. With regard to the reproductive organs of 

 Mesozoic Cycads, it is known that the majority differ in many 

 important respects from the flowers of modern Cycads, and are 

 therefore referred to a distinct group, the Bennettitaceae. The 

 structure of the male and female flowers of Bennettites is 

 described and illustrated, and compared, with those of existing 

 representatives of the Cycadales. On the other hand, a few 

 Mesozoic Cycads appear to have had flowers more like those of 

 recent members of the group, and some description of these 

 is given. 



Ginkgoales, now only represented by Ginkgo biloba were 

 exceedingly abundant in Mesozoic times, and in addition to 

 leaves agreeing almost exactly with those of the recent 

 species, there were others, which are separated as a distinct 

 genus, Baiera. Coniferales were also very common at this 

 period, especially the Araucarieae, but the Abietineae do not 

 appear to have played a prominent part before the Wealden 

 period. 



This section concludes with a discussion on the lack of 

 continuity between the floras of successive ages, and the bearing 

 of palseobotanical records on plant evolution. 



Tertiary. The section devoted to Tertiary plants begins 

 by tracing the history of Angiosperms from Lower Cretaceous 

 times. It is pointed out that the Angiosperms suddenly become 

 dominant in all known plant bearing Upper Cretaceous deposits, 

 and that the earliest types found seem to belong to living Orders, 

 and commonly are referable to existing genera. The earliest 

 member of the group known is a Monocotyledon, Alismacites 

 primaevus (figured) from the Valenginian beds of Portugal, 

 and the first Dicotyledon appears in higher strata of the same 

 beds, and is apparently an Euphorbiaceous plant, known as 

 Choffatia Franeheti (figured). These plants are from deposits 

 believed to be equivalent to the British Wealden. 



In the Potomac formation of the United States 

 (Neocomian) Angiosperms occur more abundantly. Among the 

 earliest types from the Mount Vernon series, are Casuarina, 

 Sagittaria (= f Smilax), Celaslrophyllum, etc. Monocotyledons 

 and Dicotyledons are here both represented by several types of 

 leaves. Some account is given of the flora of the other 

 divisions of the Older and Newer Potomac series, and attention 

 is called to the fact that eighty per cent of the numerous plants 

 from the Amboy Clays (Newer Potomac) are Dicotyledons, 

 and that the Amentaceae do not appear to preponderate to a 

 greater extent than they do in existing temperate floras of 

 America, to which this flora is apparently somewhat related. 



Turning to the European Upper Cretaceous, we find our next 

 Dicotyledonous Floras in beds of Cenomanian age in Mora- 

 via, Saxony, andBohemia, which appear to have been sub- 



