70 



CANADIAN FOSSILS. 



The above general sketch may serve to present a view of this remark- 

 able period in Eastern America. It might be illustrated in detail bj a 

 great number of local examples. These will be found in the Surveys of 

 :New York, Pennsylvania and other States of the American Union, in the 

 ' Report of the Survey of Canada, and in the author's "Acadian Geology." 

 In Europe such a general view is attended with greater diflSculty, owing 

 to the less breadth of the formations and the greater prevalence of local 

 diversities, and also to the want of definition in some localities between 

 the Upper Devonian and the Lower Carboniferous. Still the same divi- 

 sion into Lower, Middle and Upper Devonian exists, and the same genercl 

 relation both in fossils and physical conditions, to the Upper Silurian 

 on the one hand, and the Carboniferous on the other. 



V-l!. . n: 



(2.) Comparison with the Carboniferous Flora. 



Genetically the Flora of the Erian or Devonian is in the main identical 

 with that of the Carboniferous, and the most important and characteristic 

 Carboniferous genera are also among those best represented in the older 

 Flora. On the other hand, while some Carboniferous genera have not 

 yet been recognized in the Devonian, the latter possesses some peculiar 

 generic forms of its own, and these are especially abundant in the lower 

 part of the system. As examples of such genera I may name Psilophyton, 

 J^rototaxites, Leptophleum and Arthrostigma. Further, it may be re^ 

 marked that these peculiar Erian plants present highly composite or 

 synthetic types of structure, giving to them a more archaic air than that 

 of the Carboniferous flora. 



Perhaps the most remarkable of all the generic differences of the 

 Carboniferous and Erian flora is the occurrence in the latter of the ex- 

 ogenous genus Syringoxylon, a type altogether unknown otherwise in the 

 Palaozoic. In one point of view this may indicate the greater variety 

 and perfection of the older of the two floras. In another it may merely 

 warn us as to the imperfection of our knowledge. With regard to the 

 proportionate prevalence of particular genera, we are as yet scarcely in a 

 position to make any definite statement. Not only is our information 

 very incomplete, but there is a remarkable variety in the Devonian itself, in 

 different localities. In Gasp^, for example, Prototaxites and Psilophyton 

 are predominant forms. In New Brunswick, New York, and Ohio, these 

 forms are less abundant. In New Brunswick fronds of ferns are present 

 in great numbers, while they have scarcely been found in Gasp^ ; and 

 trunks of tree ferns and petioles without leaves have been found abundantly 

 in Ohio and New York, where fronds of these plants are comparatively 

 rare. We can scarcely at present decide whether these differences result 



