1877.] LL {Lesquereux. 
the characters described and their comparison to those of some vegetable 
of the coal is evidence of their nature. And though these remains have 
been found in old formations, wherefrom as yet no trace of land plants had 
been obtained, the doubt on that score is now removed by the discovery 
of other plants of the same kind in the Lower Silurian of North America, 
and still more by that of a Fern in the Lower Silurian of France, the 
schists of Angers, which seem to be related by synchronism to the Cin- 
cinnati Group. * 
On the character of this American formation, T. A. Miller remarks, in 
his Catalogue of American Paleozoic fossils, ‘“‘that in the Western States 
of North America, where the Utica Slate is absent from the Hudson River 
Group, the upper part of the Lower Silurian is generally called the Cincin- 
nati Group. Its strata exposed in Ohio, Indiana and Kentucky, do not 
exceed one thousand feet in thickness. The lower part is probably the 
equivalent of the upper part of the Trenton Group. The remainder 
belongs to the Hudson River Group. The total thickness of its exposure 
scarcely exceeds one thousand feet. 
Some of its characteristic fossils as Bellerophon bilobatus, Strophomena 
alternata, Zygospira modesta, Leptena sericea, Buthotrephis gracilis, Bey- 
richia chambersi, Calymene senaria, Isotelus gigas and I. megistos, pass 
entirely through the Group. Trinuclens concentricus, Triarthrus becki, 
Orthis multisecta, O. emacerata, Streptorhynchus hallia, Ambonychia 
bellistriata, Modiolopsis cincinnatiensis, Cycloconcha mediocardinalis, 
Lichenocrinus crateriformus, and Chetetes (?) jamesi, are confined to 
the lower half of the group. Glyptocrinus decadactylus, G. dyeri, G. 
nealli, G. fornshelli, Lichenoerinus tuberculatus, Streptorhynchus filitexta, 
S. subtenta, S. suleata, 8S. sinuata, S. nutans, Orthisinsculpta, O. subquad- 
rata, Rhynchonella capax, R. dentata, Cypricardites haynesi, Anomalodonta 
gigantea, A. alata, Anodontopsis millert, Favistella stellata, Tetradium fib-- 
ratum, and Streptelasma corniculum, are found only in the upper part of the 
group. Some fossils occupy only a few feet in vertical range, as Orthis 
insculpta, Orthis retrorsa, O. emacerata, Glyptocrinus nealli, and Strep- 
torhynchus suicata. 
This formation is composed in its whole of alternate layers of blue marl 
and limestone of variable thickness, the limestone layers rarely attaining 
one foot. 
* Since the preparation of this paper, I have received from Rev. H. 
Hertzer, 15th Oct., 1877, three small specimens distinctly related to the 
fragments described above by the characters and disposition of the cica- 
trices of the surface, but greatly different by the form of the bodies. One 
of them is comparable to our figure 8. It is a little larger, convex on the 
surface, and seems part of abranch. The two others, both of the same size, 
resemble gibbous tubercles, or rather small door knobs, four to five centi- 
meters in diameter, with border rounded and the upper surface flat or 
slightly convex. One of them has in the middle a scar-like depression re- 
