Lesquereux.] 168 [Oct. 19, 
The specimen of fig. 3, have the stems distinct, slightly striate, even 
slightly inflated at the articulations, a character observable only with a 
strong glass. Fig. 4 has also the stem distinctly seen between the two 
whorls, and even fig. 5 has, dimly seen, a remnant of stem as represented 
upon the figure. 
There is a difference in the size and the subdivision of the leaflets of fig. 
3; but the woody matter of the plants softened by decomposition has pene- 
trated the clay where the vegetable fragments are imbedded and the out- 
lines of the leaflets are indistinct. On one of them only the nerves are 
perceivable. The identity of the species represented by fig. 3, with those 
of figs. 4 and 5, is not ascertainable, but they all evidently represent the 
same Genus. 
There is in the Museum of Comparative Zodlogy of Cambridge a piece 
of true granite bearing remains of a fine branch of Sphenophyllum ; three 
whorls of leaves, whose stem is destroyed by decomposition, but whose 
outline and nervation are perfectly and very distinctly preserved. The 
positions of the whorls is half quincuncial, two of them placed at the base 
and one between them at a distance above ; the centres of the leaflets rep- 
resenting the three points of an equilateral triangle. 
The leaves doubly larger than those of our fig. 5, measuring two centi- 
meters in diameter, are divided into five lobes, distinct to a distance from 
the round central point of attachment to the stem ; truncate and crenate at 
the top ; with each three to five nerves ; simple at the base and forking only 
once in the middle or near the point. The divisions of the border are 
irregular as in our figure, which it represents exactly in just double size. 
We have been more than once discussing with Prof. Agassiz the origin 
of this remarkable vegetable fragment. Now that congeners are recog- 
nized in the Lower Silurian its presence upon granite is explainable, 
perhaps, as resulting from the casual deposit of a branch of Sphenophyllum 
thrown out into a basin of fresh water, upon granite rocks bordering 
swamps. Or possibly, the plant grown in place has been preserved by 
the drying and hardening of a film of decomposed vegetable matter, which 
seem to adhere to the surface of the granite, As the vegetation of the car- 
boniferous is known by remains of materials heaped in place for a long 
period of time, and preserved into the compounds formed by deposits of 
the same age, the mode of preservation of this plant upon granite, is there- 
fore different. Hence the reference to the Silurian of this branch of Spheno- 
phyllum is merely authorized by the identity of its character with those 
of the species described from the Cincinnati group. 
Habitat. Covington, opposite Cincinnati, specimen fig. 3, discovered by 
M. E. I. Ulrich. The fragments communicated by Rev. H. Herzer are 
in fine grained blue clay or marl, a compound like that where Psdlophi- 
tum gracillimum is embedded. Specimen fig. 4 was sent by Mr. Mickle- 
borough, School Principal, and found by him in the corporate limits 
of Cincinnati, in a locality known as Limekiln Run, about three 
hundred and seventy feet above low water of the river. That of fig. 
