220 MINERALS AND GEOLOGY 



within the limits of arboreal vegetation, although certain types are 

 confined to special localities. Fossil examples date from the Devo- 

 nian (or perhaps Upper Silurian period). Those 

 of Carboniferous and Jurassic strata are thought 

 to have been closely allied to the Araucarice, 

 now limited to Australia and the more southern 

 portions of South America. Pines and firs, 

 proper, first appear in Lower Cretaceousbeds, and 

 FIG. 123. are largely present in the Upper Cretaceous and 



Circular discs of conifer- T r* 11 - A i i 



ous wood. Lower Camozoic brown-coal deposits through- 



out the North- West Territories and British Columbia; whilst juni- 

 pers, yews, and gnetacese are comparatively modern types. 



In the Devonian rocks of Gaspe some casts of comparatively large 

 stems have been referred by Sir J. W. Dawson to coniferse, under 

 the name of Prototaxites, but this view is disputed by other 

 authorities. 



Angiosperms : The plants of this subdivision, as explained above, 

 comprise all flowering types in which the seeds are enclosed in an 

 ovary. They fall into two leading series : Monocotyledons and Dico- 

 tyledons. In the first, as the name implies, the embryo-plant has 

 but one cotyledon or seed-leaf ; whilst in the second, the embryo has 

 two cotyledons. 



Monocotyledons : These (formerly known as endogens) comprise 

 grasses, lilies, palms, and other representatives with (typically) 

 straight-veined leaves, flowers composed of parts in threes or sixes, 

 and wood made up of irregularly disposed vascular bundles. Obscure 

 examples are cited from Carboniferous strata, but the earliest 

 undoubted examples are Mesozoic. No fossil examples occur in the 

 strata of Ontario or Quebec. 



Dicotyledons : In these plants, the leaves are typically net-veined, 

 the flowers composed of parts in fives or fours, or multiples of these 

 numbers, and tne woody stem made up of rings of vascular bundles 

 traversed by medullary rays. The greater number of the flowering 

 plants, and all the trees (conifers excepted) of temperate regions 

 belong to this subdivision. Fossil examples appear first in Lower 

 Cretaceous strata. In Canada, so far as regards the Provinces referred 

 to in this book, the only fossil examples consist of modern leaves, 

 &c., as those of populus balsamnifera, and our common species of 



