DISTRIBUTION IN TIME AND SPACE. 69 



trace a gradual approximation to the modern types from the 

 generalized forms of Devonian and Carboniferous times. 



148. Fern Allies. Ophioglossum dates back to the Ter- 

 tiary period with one species. The order EQUISETACE^E have 

 existed since the coal period and the genus Equisetum since the 

 Triassic. The order CALAMARIACE^E, which combined charac- 

 ters of modern Equiseta and Conifers, came into existence in the 

 Devonian, but became extinct before the close of the Permian. 

 Illustrations of Calamites can be seen at the left-hand corner of 

 the frontispiece, also under the tree-fern in the centre. The 

 club- mosses proper have been in existence since the Devonian, 

 and the genus Lycopodtum since the Carboniferous. Selaginella 

 has never been found fossil, but its near relatives belonging to 

 the extinct orders LEPIDODENDRACE^E and SIGILLARIACE^E 

 were very abundant in the Palaeozoic era, particularly during 

 the Carboniferous, where they formed the largest part of the 

 forest vegetation, reaching in some instances a height of sev- 

 enty to one hundred feet. The former possessed characters 

 connecting modern club-mosses with Conifers, while the latter 

 seem to connect the club-mosses with the Cycads. Restora- 

 tions of Lepidodendron may be seen on the left-hand side of the 

 frontispiece, and of Sigillaria on the right. Isoetes dates back 

 to the Miocene (Tertiary) and Marsilia and Pilularia to the 

 same period. 



LITERATURE. 



Besides the works referred to below, many State floras will 

 give additional information respecting lucal distribution. 

 Among the more important of these are those of New Jersey 

 (Britton), Ohio (Beardslee), North Carolina (Curtiss), Wiscon- 

 sin (Lapham), Vermont (Perkins}, New Hampshire (Flint), 

 Pacific Coast (Lemmori), Illinois (Patterson), New York (Torrey), 

 Michigan (Wheeler and Smith), Indiana (Coulter and Barnes), 

 Iowa (Arthur), Minnesota (Uphani), Missouri (Tracy). 



BURGESS (T. W. J.). Recent Additions to Canadian Filici- 

 neae. In Transactions Royal Society of Canada (1886). 



which I have not seen in any variety of O. sensibilis now living." Principal 

 Dawson, however, writes: " The Onoclea sensibilis of the Laramie is truly 

 that species, and I have found with it in our Manitoba formations another 

 modern fern, Davallia tenuifolia." 



