Ammonites or Ceratites from Oregon Bar, Middle Fork of the American River.
BY PROF. WM. P. BLAKE.
The specimen which I exhibit to the Society this evening, is from the collection of J. J. Spear, of this city. It was kindly loaned to me by that gentleman for examination. Not wishing to risk the specimen, by sending it to a paleontologist at the East, I had it photographed, and sent a copy to F. B. Meek, Esq., of Washington. It is not possible to determine from the specimen, whether these fossils are new or not, or even, whether they are Ammonites or Ceratites. They appear to be not unlike the fossils described by Dr. Trask, under the name of A. Chiceonsis, Proc. Acad. Nat. Sci. Cal.; but it is not safe to identify them, without the septæ can be clearly made out.
There are several casts in an argillaceous, somewhat micaceous slate. This locality is about 15 miles from Coloma. It is not certain, whether the specimen was taken from the slates in place, or broken from a loose mass.
Mr. Moore presented the following paper: