504 PALAEONTOLOGY OF ILLINOIS. 



few species of cones (Lepidostrobi) of diminutive size, indicating there the dis- 

 appearance of the large Lycopodiaceous plants which afterwards were not re- 

 presented in any of the formations of our earth. 



The fruits described under the generic names of Trigonocarpus, Rhabdocarpus, 

 and Ptilocarpus, have as yet been found only from the Sub-Conglomerate coal 

 strata upwards to coal No. 2. They abound in the Millstone grit and the 

 hearth sandstone, as in the shale of coal No. 2. A few fruits of uncertain 

 affinity, and considered under the name of Carpolithes, have been observed 

 higher in the Measures ; for example, Carpolithesfasciculatus, at Grayville, Ills. 

 As yet these cases are very rare. 



As to the ferns, the distribution at different horizons is more striking in 

 considering certain groups or races, rather than peculiar genera or species. 

 The genus Neuropteris, for example, is equally well represented, from the Sub- 

 Conglomerate coal of Arkansas to the highest strata of Pennsylvania and Ken- 

 tucky, by Neuropteris hirsuta, Neuropteris flexuosa, and Neuropteris Loschii, all 

 species closely related by their peculiar nervation. These are, moreover, 

 universally distributed over the whole extent of our coal fields, and in Europe 

 two, at least, ascend to the Permian. From this group, Neuropteris tenuifolia 

 is the only one which, appearing with the Sub-Conglomerate coal, has not as 

 yet been found higher than coal No. 2. Another section of this genus, espe- 

 cially comprising species of a coarse or thick nervation or texture, like Neu- 

 ropteris Clarksonii, N. rctrinervis, N. vermicularis, N. coriacea, N. pachyderm, 

 etc., is as yet truly characteristic of coal No. 2, none of them having as yet 

 been found above or below it. All the species of the genus Odontopteris ap- 

 pear distributed from the coal strata under the Millstone grit up to coal No. 1 

 and No. 2. In Illinois, as in Pennsylvania, most of the species are found in 

 connection with the last bed. It is the same with the species of large, thick 

 leaved Alethopteris, A. lonchitica, A. Serlii, A. Mazoniana, A. Massillonis, . A, 

 Owenii, etc. They form, with Callipteris Sullivantii, a distinct and peculiar 

 group, which may be considered truly characteristic of coal No. 2. AktJiopteris 

 lonchitica, has always been for me an essential leading species, and never, as 

 yet, has misled me as marking the horizon of the mammoth vein of Penna. 

 In the east, it is a most common species ; it abounds also at Cuyahoga Falls, 

 Ohio ; but it seems to disappear in some basins, as for example in Illinois, 

 where its place is taken by Alethopteris Serlii and Callipteris Sullivantii. 



Of Pecopteris, the section which Brongniart separates under the name of 

 Sphenopteroides, and which Schimper rightly places in the genus Sphenopteri S} 

 is the only one which may be considered as yet as peculiar to the lower Coal 

 Measures. Its species, Pecopteris Murrayana, P. chosrophylloides, P. Newlerryi. 

 with Sphenopteris latifolia, S. oltusiloba, and 8. acuta } are found in connection 



