504 PAL2EONTOLOGY 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, Carpolithes fasciculatus , 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 Jlexuosa , 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. Prom 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 Clarhsonii, N. rarinervis, N. vermicularis, N. coriacea, N. pacing derma, 
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 Sirtlibantii, a 'dibilribt' in'd peculiar 
group, which may be considered truly characteristic of coal No. 2. Alethopteris 
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 Palls, 
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 
Sphenopteroules, and which Schimper rightly places in the genus Sphenopteris, 
is the only one which may be considered as yet as peculiar to the lower Coal 
Measures. Its species, Pecopteris Murrayana, P. cheerophylloides, P. Newberryi . 
with Sphenopteris latifolia, S. obtusiloba, and S. acuta y are found in connection 
