GEOLOGICAL SURVEY OF THE TEEEITORIES. 315 



No species of Glumaceoe is as yet known from the Cretaceous forma- 

 tions of this continent, but from uncertain remains, knots separated 

 from the stem, and a piece of a stem referable to the genus Arundo. As 

 Gkimacece and Cyperacecc are kirgely represented in the Tertiary, we 

 may expect to find types of these orders of plants in some strata of the 

 Upper Cretaceous, their distribution being local, as remarked formerly. 

 Per contra, the Cretaceous has already typical representatives of the 

 essential sections of the Gyrnnospermw, as they are seen later in the Ter- 

 tiary and now in our flora. The Gupressinece are represented by Glyptos- 

 tr ohus gracilUmiis, Jjsqx.', the AhietineoB, hyAraucaria (?) spaffmlata, Newby, 

 Sequoia formosa, Lsqx., a cone of AMetites described as Pteropliyllum, (?) 

 Lsqx., ail these from Nebraska and Sequoia ReichenhacJii, Heer, from Mon- 

 tana. These are followed in the Tertiary by a number of forms of Taxo- 

 dium, Glyptostrohus^ Sequoia, &c., all repeated without striking variations 

 in our flora. Sequoia is well represented in the Miocene of Europe ; but 

 this genus has disappeared from its flora, as also from our northeastern 

 American flora, being still distributed in California. The type of our 

 AMes appears to be Araucaria spathulata, named above, a form referable 

 to three species of Abietites, described by Dunker from the Quader- 

 sandstein of Blankenburg, and which, altogether, may represent a single 

 species. As yet we have no remains of Pinus^ neither from the Creta- 

 ceous nor from the Tertiary. Heer has, however, described two species 

 from the Cretaceous of Greenland, and twenty- four species from the 

 arctic Tertiary. That they have not been found yet in the North 

 American measures, is merely the result of the geographical distribution 

 of the species of this genus. A remarkable group of the Taxinece, repre- 

 sented already in our Cretaceous by one species of Fhyllocladus, and in the 

 Lower Tertiary by a Salishuria, is out of our present flora. The species 

 of the first genus inhabit New Holland and Tasmania 5 the other has only 

 one living representative species in Japan. Nothing can be said on the 

 causes of migration, and extinction of vegetable types. As Australia has 

 now animal species analogous to those of the Cretaceous, it would not be 

 peculiar to find there also the same kind of analogy for lilants. Species, 

 especially of conifers, disappear without appreciable causes, as some 

 of them are now dying out at our time 5 the cedar of Lebanon, the pine 

 (Pinus cembra) of the xllps, the giant trees of California, {Sequoia, &c.) 

 That our climate is well appropriate to the vegetation of Salisburia 

 adiantifolia is proved by the result of its culture. There is in the rovr 

 of trees bordering the Common of Boston, a splendid representative of 

 this species, witli a trunk about one foot in diameter. It has never been 

 sheltered, and is there mixed with elms and other indigenous species. 



But the conifers do not furnish the essential characters to our present 

 arborescent flora. Most of the trees of our forests belong to the first 

 division of the dicotyledonous plants, that of the apetalous; the sweet- 

 gum, the willow, the poplar, the oak, the beach, the elm, &c., are of 

 this kin<l. 



Already one species of Liquidambar is known from its remains in the 

 Cretaceous, L. subintegrifolius, intimately related to another species, L. 

 gracile, of the Lower Tertiary of the West. Both are remarkable for the 

 entire borders of the leaves; but for this, theform of the Cretaceous leaf 

 is similar to that of L. styraciflua. our sweet-gum. Two si)ecies arc also 

 represented in the Miocene of Europe. Of the poplars, already seven 

 species have been described from tlie Cretaceous of Nebraska. The 

 types of our actual species are marked there alread^^, and more still in 

 the species of the Tertijiry, (21,) some of them identical with those of 

 the same formation of Europe. The willows have five species in the 



