13 



Monopetalce, and Polypetalce. The first that we can find are, 

 to use Dr. Carruther's words, "not generalised types, but 

 differentiated forms, which, during the intervening epochs, 

 have not developed even into higher generic groups." 



To take, for instance, the Dakota group in North America, 

 among its 130 species, as yet known, only one may be doubt- 

 fully referred to the Cycads ; there are only five Cryptogams, 

 six Conifers, and two Monocotyledons ; all the rest are Dico- 

 tyledons, distributed into genera, much, as now ; of Apetalce 

 it has Amentacece, Myricacece, Plataneas, Salicinece ; of 

 Gamopetalce, Bicornes, Ebenacece, &c. ; of Polypetalce, Mag- 

 iioliacece, Sapindacece, Menispermacece, &c. As Dr. Les- 

 quereux says (Cretaceous Flora, p. 38) : " It has represen- 

 tatives of all the classes of plants, without disproportion, in 

 one degree or the other, as compared to what is considered 

 the scale of the vegetable kingdom. This seems to prove a 

 collateral development of different primitive types, and, 

 therefore, the appearance at certain epochs of those original 

 forms which, at each geological period, have changed the 

 character of the vegetable world, and which do not have any 

 connexion with antecedent types." Again, still more de- 

 cidedly (p. 35), after remarking that it is easy to build up 

 imaginary systems of derivation from supposed simple types, 

 by mere deviations or multiplications of organs, he goes on: 

 " But until we know more we have to consider the facts. 

 And the conclusion evidently forced, at least in considering 

 the flora of the Dakota group, is that its disconnexion from 

 ancient types is so wide that even the supposition of inter- 

 mediate, unknown, extinct vegetable types fails to account 

 for the origination of its peculiar characters." 



So far as the evidence of the Upper Cretaceous Dicotyle- 

 donous remains goes, it is decidedly opposed to the theory of 

 descent. It is opposed to it in two ways. First, by the 

 sudden emergence of the class already differentiated into sub- 

 groups it irresistibly suggests some abrupt origin of that 

 class, such as immediate creation. Secondly, by the proof of 

 the persistence of generic types so complicated as that of the 

 tulip-tree from that distant period to the present day without 

 any apparent change, it negatives any theory which is built 

 upon the indefinite variability of systematic characters. 



8. The Flora of the Coal Measures. We now come to the 

 most fascinating of all the extinct floras, that of the Palaaozoic 

 Coal Measures. The imagination is wonderfully attracted by 

 the picture which science calls up of these old-world forests. 

 Stretching for hundreds of miles along the swampy margins 

 of estuaries, and covering the surface of their low deltas, they 



