448 SKETCH OF PALEOBOTANY. 



all other types. But that the pine family is now waning there can be 

 no doabt. Important forms have wholly disappeared, and others that 

 once were abundant have now nearly vanished from the earth. Of this 

 last truth an example of unusual interest is furnished by the genus 

 Sequoia. Of the score or more of species that made up so large a part 

 of American Tertiary forests our well-known " big tree" of the Sierras 

 {8. gigantea) and our California red-wood {8. sempervirens) now stand 

 alone and continue the combat against fate — the closing straggle of a 

 dying race. 



Of the Onetacece I need not here speak, as its paleontological record 

 is almost nil, and its importance depends upon circumstances wholly 

 disconnected from its prevalence as a type of vegetation. 



We come now to the Angiosperms. A groat step forward had been 

 taken, and in her solicitude for her offspring Nature had, as it were, 

 buUt a house over the hitherto unprotected germs of plant life. The 

 closed ovary marks an era in the march of vegetal development. 



The earliest form in which the Angiosperms appeared was that of 

 the Monocotyledon. Issuing from the seed and from the ground as a 

 single spear or blade, the plants of this type grow up chiefly by an in- 

 ternal circulation which can only deposit nutrition at the apex (endo- 

 genous growth). As the lowest type of Angiosperms we find them, 

 according to our scheme of classification, occupying also the earliest 

 position in the stratified deposits of the earth's crust. 



The existence of Monocotyledons in the Carboniferous and Permian 

 was long disputed, although Corda, after the most exhaustive study of 

 their structure, was obliged to refer two species of endogenous wood 

 to that subclass. This determination has been thus far sustained, and 

 to these have been added Falceospathe Sternbergii, Unger, in the Car- 

 boniferous, and two other species in the Permian. The very problem- 

 atical Spirangium has generally been regarded as the fruit of some 

 Xyrislike Monocotyledon, and this view has been quite recently de- 

 fended by Nathorst. Its occurrence in the Carboniferous is now also 

 abundantly established by its discovery at Wettin, at Saint Etienne, and 

 at Pittston, Pennsylvania. Certain lily-like forms, called Yuccites, are 

 found in the lower Trias, and through the remaining Mesozoic these forms 

 increase slowly and are reinforced by screw-pines and a few sedge-like 

 plants. The monocotyledonous vegetation, however, does not receive 

 any marked character until the advent of the great palm family, which 

 dates from the Middle Cretaceous. From this time, notwithstanding 

 the rivalry of the now dominant Dicotyledons, this type progressed, 

 reaching its relative maximum in the Eocene. Overslaughed by the 

 higher growths, it thenceforward declined, but still numbers some 

 20,000 species and forms over one-eighth of the total flora of the pres- 

 ent epoch. 



The step from the Monocotyledon to the Dicotyledon is very great, 

 and it seems to have required a vast period of time to accomplish it. 



