Note on the discovery of Fossils in the Auriferous Slate formation of the Mariposa Estate, California, and the probable geological age.
BY PROF. WM. P. BLAKE.
During a recent visit to the Mariposa Estate, Mariposa County, my attention was called to some organic remains in the slates, near Bear Valley, by Miss Errington, a lady who takes an enthusiastic interest in the sciences of geology and mineralogy, and has for some time past, been seeking for fossils in the gold formation of that neighborhood. One of the specimens was the cast of a bivalve shell, and appeared to me to be a Plagiostoma. On further search, we found other specimens, some of which much resemble Inoceramus, to which I am inclined to refer them. Certain long tubular cavities in the slates, marked with heavy lines, and slightly converging, seemed to be casts of long, nearly cylindrical shells, possibly Nerinæa. These forms would indicate a Jurassic or Cretaceous age for the formation. I propose to submit these specimens to a competent Palæontologist, at the East, for examination, and to dedicate one of the species, if new, to Miss Errington.