and their allies (Pteridophyta) represented by Leptdodendron, 

 Sigillaria and Catamites, and the early seed-bearing plants, 

 the cone-bearers (Gymnosperms), represented by Cordaites, 

 with the fossils under Trigonocarpon, Rhabdocarpon, and 

 other genera. 



In the second floor-case are representatives of Palaeozoic 

 Time: Carboniferous Period. — The specimens in this case 

 are exclusively ferns or plant-remains which were originally 

 described as ferns but which are now thought to belong to a 

 different group, the Cycadofilicales, that is, plants that had 

 characteristics of both the ferns and the sago-palms, but 

 rather more closely related to the cone-bearing trees than to 

 the ferns. 



The third floor-case contains types of Mesozoic Time : 

 Triassic and Jurassic Periods. — The plant-remains in this 

 case are mostly sago-palms or cycads, with some other cone- 

 bearers and fern-plants. 



The fourth floor-case embraces plant-remains from the 

 rocks of Mesozoic Time : Lower and Middle Cretaceous 

 Period. — These specimens represent the first appearance of 

 the fruit-bearing plants (angiosperms), the type which is 

 dominant in the existing flora. The genera are in most in- 

 stances apparently identical with those now in existence, but 

 the species are extinct. The plants of the Lower Cretaceous 

 period consist largely of ferns and cone-bearers, while those 

 of the Middle Cretaceous show a preponderance of seed- 

 bearers. The specimens from the Dakota Group of Western 

 America are exceptionally fine, many of them being perfectly 

 preserved and showing both cast and impression of the same 

 leaf. 



The fifth floor-case contains the plant remains of Mesozoic 

 Time : Middle and Upper Cretaceous Period. Here may 

 be seen interesting specimens of the fossil floras of both 

 eastern and western North America, including the ancestors 

 of our living tulip-tree (Liriodendroii). 



In the sixth floor-case may be seen the plant-remains of 

 Neozoic Time : Tertiary, Quaternary and Recent or Modern 



