184 * GEOLOGY. 



to which they belonged are still represented in our existing flora. 

 The collection of these leaves has steadily gone on until the pres- 

 ent time, some of the most important being made by Meek and 

 Hay den in 1S56 and 1S57, and again in 1S65. Prof. Newberry 

 also engaged in this work in another field. Prof. Marcou and 

 Capellini also added to the number, as well as Prof. James Hall, 

 Lesquereux and Prof. Mudge. One of the first published reports, 

 with drawings of the leaves, was that of Prof. O. Heer, of Swit- 

 zerland. In 1S74 the Hayden surveys published Lesquereux' Da- 

 kota Group, Cretaceous Flora, which combined all the previously 

 published descriptions, with a great deal of original matter, and 

 gave a full description of all these leaf impressions that had been 

 discovered up to that time. According to this report there have 

 been found thus far in this group 132 species, distributed among 

 seventy-two genera. Of these there were of non-flowering plants 

 seven species, and six of these were ferns. Of naked seeded 

 plants (Gymnosperms) there were seven species, one of which was 

 a zamias and six coniferas. Two of these belonged to the giant 

 cedar family (Sequoia), and one a glyptostrobus, similar to the one 

 still growing in China and Japan. There were three moncoty- 

 ledons, one of which was a palm. The dicotyledonous trees, called 

 also exogens {outside grotuers), to which division all our common 

 trees belong, were the most fully represented, all the remaining 

 forms belonging to these classes. Among these there were five 

 species of populus, the genus to which our cottonwood belongs. 

 Closely allied to the last were four species of populites. Of the 

 willows (Salix), there were six species. The oaks (Quercus), were 

 represented by eight species, and the beeches (Fagus), by two. 

 There were six species of buttonwood (Platanus), and one fig 

 tree. There were two species of spicewood (Laurus), seven of 

 sassafras and two of cinnamonum. The magnolias were abundant, 

 as the presence of fine species attest. The tulip trees (Lirioden- 

 dron), which are among the most magnificent of all modern trees, 

 were represented by three species. One buckthorn (Rhamnus), 

 one walnut (Juglans), and one sumac (Rhus), have left their re- 

 mains in this group. Even an apple (Pyrus), and a plum (Prunus) y 

 flourished in those times. 



No one, however, can get a clear idea of the character of this 

 rich modern flora without studying its remains, or the remarkable 

 and beautiful report of Lesquereux on " The Fossil Flora of the Da- 



