FLORA OF THE KOOTANIE FORMATION. 293 



separation as even a variety. These pinnules are commonly longer 

 and narrower, especially toward their tips, which narrow more gradually 

 than those of the Virginia plant. They are also more acute. No forms 

 were found in the Virginia specimens that showed any indication of 

 undulation or lobing. Although these differences are slight, and hence 

 of no great weight, it seems to be the better usage, in the case of plants 

 that grew in widely separated locaUties, to allow them more weight 

 in separating than in uniting forms. The presumption is that the plants 

 are different, and the burden of proof is with the person who would 

 unite them. Nonessential features that are not admitted as justifying 

 the formation of new species certainly can not be taken as establishing 

 the identity of plants that grew in situations separated by thousands 

 of miles. Still less can such features be admitted as indicating iden- 

 tity, when the plants grew in different times. Then, too, if the new 

 species or variety turns out to be identical with some known form it 

 is easier to drop its name than to restore it to independence when it is 

 shown to have been improperly merged with some previously described 

 plant. 



PI. LXXI, Fig. 14, represents a portion of a pinna carrying parts 

 of a number of pinnules with undulate margins. It will give a good 

 idea of the size that the rachis of the pinnae attained, but unfortunately 

 the pinnules are not well enough preserved to give their full dimensions 

 and shape. Fig. 15 gives a portion of a crenatel)^ incised pinnule, which, 

 when entire, was evidently considerably longer than the specimen. 

 Some of the crenate pinnules found are wider than this bj^ a half. Fig. 

 16 represents one of the lobes enlarged to show the nervation. Fig. 17 

 gives a fragment of one of the pinnse containing a number of normal 

 entire pinnules from the middle portion of a pinna and frond. Fig. 18 

 represents a pinnule of this magnified to show the nervation. A num- 

 ber of the pinnules of this specimen show on their surface markings 

 that look strikingly like elliptical sori. They are, however, not placed 

 according to any definite plan, but occur on any part of the pinnule, 

 sometimes on different nerves and on different parts of them and some- 

 times between the nerves. They are probably clue to some fungoid 

 disease. Fig. 19 shows the terminal portion of a pinna, with the dimi- 

 nution in that part of the size of the pinnules and their increasing con- 

 solidation toward the ends of the pinnse. 



