Page:The Habitat of the Eurypterida.djvu/122

 on flood-plains or the lower reaches of two rivers, then the lithological peculiarities of the deposit are readily explained. In that case we would expect these muds to become more marine southward, where they are now covered, and where the subaqueous delta part was situated. Between the deltas the Bertie should be impressed with certain marine characters, as it actually is in sections in Cayuga and Ontario Counties. In the Auburn-Geneva quadrangle, Cayuga

County, the Bertie is an evenly bedded, impure, magnesian limestone, which when freshly broken is dark colored and of medium hardness. In portions it shows faint deposition lines, but heavier layers, from one to two feet thick, are usually quite compact. Some layers weather into a hard slaty shale. The fossils which have been found are: a few Lingulas, two species; one Orbiculoidea, a Rhynchonella, Leperditia alta, and fragments of eurypterids. In the