410 H. D. Rogers's Observations on 



beds of anthracite in the coal-fields of eastern Pennsylvania, 

 which, compared with the bituminous coal-measures of western 

 Pennsylvania, appear not only to contain a greater variety of 

 species, but to present them in a condition of more perfect 

 preservation for study. 



The new species here briefly described by Mr. Lesquereux, 

 constitute about one half of the total number of well-defined 

 forms hitherto detected by him in the coal-measures and lower 

 carboniferous rocks (the vespertine series) of Pennsylvania; 

 more than one hundred of the two hundred and twenty spe- 

 cies examined by him proving to be entirely identical with 

 species already recognized in the European coal-fields, and 

 some fifty more of them showing differences so slight, that a 

 fuller comparison with better specimens, may result in their 

 identification likewise. As a further evidence of the near 

 affinity of the North American to the European fossil flora of 

 the carboniferous age, he has remarked, in the course of his 

 investigations, that even these new species which seem re- 

 stricted to this continent, are every one of them in close rela- 

 tionship with European forms. It deserves mention, more- 

 over, that the commonest European species are likewise the 

 most common American ones. 



A stratigraphical analysis of the anthracite measures of 

 Pennsylvania, calls for their division into two groups, a lower 

 series, distinguished by the white or very pale color of the 

 ashes of nearly all the coal seams, and an upper series, in- 

 cluding coals as remarkable for yielding only pinkish or red 

 ashes. Between these groups there usually exists, especially 

 in the southern or Pottsville basin, a small transition group of 

 two or three beds of gray ash, or pinkish-gray ash coals. The 

 entire number of coal-seams, of a thickness admitting mining, 

 in the middle portion of the southern basin, where the whole 

 formation is thickest and most replete in coal-beds, does not 

 exceed about twenty-five ; and counting those of all dimen- 

 sions, the total series does not amount to more than from 

 thirty to thirty-five separate layers. 



