Lesquereux. ] 172 | Oct. 19, 
The schists of Calymene Tristani, where the fern mentioned above was 
recently discovered, have been considered by Dufrenoy asan upper member 
of the Caradoc sandstone of Great Britain. The Cincinnati Group is 
generally referred to this formation. Its relation, however, to the schists 
of Angers is not positively fixed. The preponderance of species of Caly- 
mené like C. senaria; of analogous Genera, Triarthrus becki, ete., so 
common in the blue shale of the Cincinnati epoch, seem to indicate a close 
relation between both formations of Europe and of America. The enumera- 
tion of fossils considered characteristic of the Cincinnati group may afford 
by comparison more positive evidence of the geological relation of the 
strata where the first Silurian remains of land plants have been found. 
It isa remarkable fact that the character of these Silurian plants, described 
above, give us like a microcosmical representation of the flora of the Carbon- 
iferous, so simple and at the same time so admirable in the multiple sub- 
divisions of its specific forms. The coal flora is a compound mostly of 
vascular cryptogamous plants : Lycopodiace, Ferns and Equisetacez, and 
of some Phrenogamous Gymnosperms whose types are apparently related 
to the Cycade or to the conifers. 
We now have represented in the Silurian, 
Ist. The Lycopodiacee, by species of Psilophitum,; diminutive forms but 
primitive types of the Lepidodendra, represented in the coal by very large 
trees distributed in a number of generic and specific divisions. 
2d. The Ferns, by a species related to Paleopteris or to the group of the 
Neuropteride which makes the finest and most common species of the coal. 
The fern of the schists of Angers is named Hopteris Andegaversis by 
Saporta, who discovered it. 
dd. The Calamarie, by Sphenophyllum and Annularia; these forming 
two sections related to the Hquisetacew, but whose vegetable affinity is 
not satisfactorily ascertained. They represent Cryptogamous acrogens like 
the ferns. 
6th. The Sigillariw, placed by some authors as an order of plants 
between the Conifers and the Cycadex, or representatives of the Phseno- 
gamous gymnosperm. We have, it seems, a species of this group in the 
Protostigma. 
The Cordaites now are considered Conifers. 
From the preponderance of large fossil trunks of Conifers in the Devo- 
sembling the point of attachment of a tuft of leaves. Both are marked 
around on the borders and upon the top surface by rhomboidal cicatrices 
in spiral order like those of our figure 7. Some of these especially along 
the border are deep and have very distinct central mammille like points of 
vascular scars. These organized bodies are attached to broken pieces of 
Silurian limestone, bearing upon the lower part fragments of small marine 
mollusks. “This, together with their shape, their convex or flattened sur- 
face, seems to prevent their reference to Sigilluriotd plants. They look 
however like miniature trunks of Cycadew, which for many of their species 
