280 GEOLOGICAL SUEVEY OF THE TERRITORIES. 



Sphenopteris crassa, described by the same author from the same forma- 

 tion, the Posidonien schieffer. The examination of a large collection of 

 specimens from the coal-measures of Alabama affords the means of 

 pursuing the comparison of these floras somewhat further, for, till now, 

 the subconglomerate coal flora was merely known by the species de- 

 scribed from Arkansas.* That of Alabama is composed of a large 

 number of species as yet unobserved in this country ; some of them, 

 however, described by European authors, by Brougniart, Lindley, and 

 Hutton, especially, from the lowest coal-beds of England and of Ger- 

 many, inferior in station to the millstone grit. 



There is, forexample, Sphenopteris Hoeninghausii, predominant by an 

 immense number of specimens ; three species of Eremopteris a coarse- 

 veined Neuropteris, recalling the type of Paleopteris of the Old Eed ; 

 many Lepidodendron, some identical with species of the measures above 

 the conglomerate ; some of a peculiar type, one especially, with branches 

 covered both by leaves and scales, and Ulodendron minus, of the Lower 

 Carboniferous of England. Hence we have in the subconglomerate 

 cOal of Arkansas and of Alabama another intermediate flora uniting 

 types of the coal above the millstone grit with those of the Perry shales, 

 as these serve as point of transition between the Gatskill flora and that 

 of the subconglomerate coal. It is thus to this point an uninterrupted 

 series of vegetable forms.t 



The characters of the floras of both stages of the Carboniferous over- 

 lying the conglomerate are well known. The lower, in connection with 

 beds of coal of remarkable thickness, especially in the anthracite fields 

 of Pennsylvania, has a profusion of Lycopodiaceous. There abound 

 species of Lepidodendron, Ulodendron, Knorria, genera represented 

 mostly by very large trees; some ribbed Sigillarice; large-leafed species 

 of Alethopteris, of a type probably derived of the Megalopteris of old, like 

 A. JSerlii, A. Sullwantii, A. pennsylvanica, A. lonchitico, with its numerous 

 varieties, A. nervosa, which, like the former, appears already in numer- 

 ous specimens in the flora of the Alabama coal : Sphenopteris, species 

 also related by their character to those of Arkansas, like S. Gravenhorstii, 

 S. decipiens ; numerous species of Hymenophyllites, and hard fruits, Gar- 

 polithes, Gardiocarpi, and Trigonocarpi. All this gives to the supra-con- 

 glomerate coal a character which is especially predominant in the low- 

 est beds. In passing up to the Pittsburgh division, or to the upper 

 coal-measures, the constituents of the flora are gradually modified by 

 the decreasing number of the great lycopodiaceous species, w r hich are 

 rarely found above the Mahoning sandstone of Pennsylvania, aud by a 

 proportionate increase of the Sigillarice species, especially of the ecostate 

 section. We have in these upper coal-measures, besides these Sigilla- 

 rice, a preponderance of ferns, arborescent species of Pecopteris, whose 

 large fronds and pinnae are spread upon the shale like small trees; 

 Pecopteris arborescens, P. unita ; some bushy Neuropteridece ; Neuropteris 

 Loschii, especially the most common of all; a profusion of Galamites and 

 Gordaites, and still one species of Alethopteris, A. aquilina, a diminutive 

 form. Whenever remains of fossil plants are found in connection with 

 a coal, paleontology easily recognizes their relation to the upper or to 

 the lower division of the supra-conglomerate Carboniferous measures. 

 From this it follows that from the base of the Catskill group to that of 



* Geological Report of Arkansas, vol. ii, pp. 295-319. 



t Prof. E. T. Cox, State geologist of Illinois, has quite recently sent me for determination 

 a box of specimens from the whetstone grit, 25 feet lower than the base of the conglomei ate. 

 They represent species either identical with or intimately allied to those of the flora of the 

 subconglomerate coal of Alabama. 



