lesquereux.] EVIDENCE OF AGE OF LIGNITIC GROUP. 279 



species of plants described by Prof. B. P. Meek, in proceedings of the 

 Washington Philosophical Society (1872). The specimens, which repre- 

 sent tbree very fine species of Paleopteris, a Lepidodendron, a Siigmaria, 

 and a Carpolithes, were obtained from Lewis's tunnel, Alleghany County, 

 Virginia, in the lower part of the Sub-Carboniferous measures, near its 

 junction with the Upper Devonian. 



Until recently there was, between these species of plants of the Cats- 

 kill and those of the Carboniferous type, a break of relation which 

 could not be accounted for, except by the supposition of a change of 

 formation, as it has been generally done for interruptions of this kind. 

 Therefore, the reference of the Catskill beds to the Devonian was judi- 

 cious so far ; but, two or three years ago, Prof. E. B. Andrew, while 

 connected with the geological survey of Ohio, discovered, in Perry 

 County, in the southern part of this State, a bed of black shale, with 

 abundant, well-preserved remains of ferns of peculiar and remarkable 

 type. These shale, from the remarks of Professor Andrew, are at a dis- 

 tance above the Chester limestone, or on the upper part of the so-called 

 Sub-Carboniferous measures of the West. Somewhat later, Mr. I. H. 

 Southwell, of Port Byron, Illinois, sent from that locality, as discovered, 

 also, in a bed of soft black shale, underlying the true Carboniferous 

 measures, a number of specimens representing some of the most pre- 

 dominant forms observed in the shale of Perry County. This pecu- 

 liar group of plants has still two species of Paleopteris, one of them 

 closely allied to P. Jacksoni, the other, like P. obtusa, figured in Dana's 

 Manual of Geology, with some of the pinnules deeply emarginate at 

 the top, or bilobed. The majority of its species, however, are referred 

 to Megalopteris, a new genus established by Dawson, and represented 

 by ferns with immense fronds, large decurring leaflets, often divided in 

 the middle, in two lobes, by the forking of the middle nerve. One species, 

 of about the same character, is described by Professor Andrew* under 

 the generic name of Orthogoniopteris. The specimens from Port Byron, 

 111., represent, also, more generally, species of Megalopteris, one of them 

 especially remarkable by the agglomeration or tufting of the terminal 

 leaflets, which divide, above the base, in two, more rarely three, equal 

 lobes, by the forking of the middle nerve, as remarked above. This 

 mode of division of the leaflets is exceptional in ferns of this kind, and 

 has never been observed except in one species of the lowest coal-bed oi 

 Illinois, the first above the millstone grit, and described in the 4th volume 

 of the Geological Reports of that State as Newopteris fasciculataA 



Professor Schimper, in his Vegetable Paleontology, mentions this 

 species as a very singular one ; and the discovery, in a lower member of 

 the Carboniferous, of species t® which this peculiar conformation is trace- 

 able, affords a point of comparison which cannot be overlooked in search- 

 ing either for geological relation or for an affinity of vegetable types. 

 Allied to the plants of the Catskill group by its Paleopteris, to the so- 

 called Upper Devonian of Canada by the Megalopteris, the flora of Port 

 Byron passes to that of the subconglomerate Carboniferous of Arkan- 

 sas by a small Arterophyllites, A. gracilis, which is present, also, in the 

 shales of Perry County, and described, too, in the Pre-Carbonil'erous 

 flora of Canada as A. parvula ; by Lepidodendron modulatum and L. car- 

 •inatum, two species found also in Arkansas in subconglomerate coal- 

 beds; by Cardiocarpon Southwellii, similar to C. ingens, of Arkansas ; 

 and it has, also, one species, Sagenaria depressa, Gopp. of the Culm 

 or Sub-Carboniferous of Europe, and another intimately allied to 



* Journal Science and Arts, December, J 875, pp. 462-466. 

 t P. 381, PI. V, Figs. 1-4. 



