UPPER CARBONIFEROUS 133 



the typical Permian deposits of Russia represent local and not normally 

 marine conditions of deposition. 



I am tentatively assuming, on the grounds noted above, that the 

 Guadalupian is equivalent to the Permian or to the Permian and 

 Artinskian, the one representing a normal marine and the other an 

 abnormal facies. It may prove, however, that all or part of the 

 Guadalupian is younger than the Permian. A recent monograph by 

 Tschernyschew gives a complete account of the brachiopods of the 

 Gschelian, but the other types remain undescribed or else the descrip- 

 tions are badly scattered. The literature on the Artinskian and Per- 

 mian is also somewhat scattered, but one receives the impression 

 that the brachiopods of the latter do not present many positive differ- 

 ences from those of the Gschelian though much less varied, and 

 reduced to a few types of long range and wide distribution. Whether 

 the same is true of the rest of the fauna it is difficult to say, although 

 it seems rather doubtful. In view of the striking difference between 

 the faunas of the Guadalupian and the Hueco formation, in which the 

 brachiopods are most in point, of a lack of a corresponding difference 

 between the Gschelian and Permian, of the marked resemblance of the 

 brachiopods of the Hueco and Gschelian, and of the lack of agreement 

 between the Permian and Guadalupian, there is a possibility, if not 

 a certain probability, that the Artinsk and Permian may be correlated 

 with the Hueco formation. 



Having compared the western faunas with those of Russia, let us 

 consider what their relations may be with those of eastern North 

 America. 



We find in such a comparison really fewer resemblances than with 

 the faunas of Russia. Of the three or four western faunas which 

 I have noted, by far the greatest resemblance is to be found in the 

 oldest of all; perhaps because it is least varied and most generalized. 

 The Hueconian presents much more numerous and extensive differ- 

 ences and the Guadalupian the strongest of all. In fact, of the 325 

 species recognized in the latter scarcely a single variety can be definitely 

 identified in the eastern faunas. The species are in most cases not only 

 not the same but they are not even similar. It seems possible to me 

 that the Hueconian fauna may be equivalent, in spite of its differences, 

 to the faunas of the East, but hardly that of the Guadalupian. This 



