OF CENTRAL CANADA PART IV. 



219 



PHANEROGAMS. 



All flower-bearing vegetable forms belong to this division ; but in 

 many, the flowers are exceedingly inconspicuous, being destitute of 

 corolla and other parts of the floral enve- 

 lope or perianth, and thus reduced to parts 

 directly concerned in the production of seed. 

 The phanerogams fall into two principal 

 series : Gymnosperms and Angiosperms. In 

 the first, the seeds are "naked," that is, 

 they are not developed within a special 

 ovary ; and these types present in other re- 

 spects certain peculiarities of organization 

 which, notwithstanding the exogenous struc- FIG 122 



ture of the wood, render them more or less Cordaites angusti/oiia (Dawson). 



, . ,11-1 T i Devonian: Gaspe. 



akin to the higher cryptogams. In the an- See preceding paragraph 

 giosperms, on the other hand, the ovules are developed and con- 

 verted into seed within a special receptacle or so-called ovary. 



Gymnosperms : These, distinguished essentially by their naked 

 seeds, are commonly classed under three orders : Cycads, Conifers, 

 Gmtacece ; but the latter, some of which are known popularly as 

 "jointed firs," are of no palaBontological importance. 



Cycads, represented essentially by the genera cycas and zamia, are 

 intermediate in aspect between tree-ferns and palms ; and those of 

 existing Nature are entirely confined to intertropical regions. .Fossil 

 forms are cited from Devonian and higher strata, and are especially 

 characteristic of Mesozoic formations. (See the table on page 201.) 

 Examples are unknown within the area of Central Canada. 



Conifers comprise firs, pines, cypresses, and other (typically) cone- 

 bearing, resin-secreting types, with acicular or narrow leaves. 

 Vertical sections of the wood shew under the microscope rows of 

 circular discs, regarded practically, as a typical character ; but these 

 discs are shewn also by cycads, and likewise, although far less pro- 

 minently, by certain dicotyledons. Conifers occur in all latitudes 



4. Sigillaria .-Stem-forms, with (typically) longitudinal ribs and grooves on the surface, 

 and with more or less hexagonal or oval leaf-scars within the furrows. The scars in some 

 examples are comparatively far apart ; in others, close together. Some examples, also, are 

 without longitudinal ribs and furrows. Dev. , Carb . 



5. Stigmaria .-Stem-like casts with irregular, more or less rounded, surface-markings. 

 Supposed roots of sigillarise and lepidodendra. 



