8. Lepidotus Haydeni, Leidy.

A species proposed on a single specimen of a thick oblong square seale, the long sides of which measure 5 lines, and the short sides 3 1/2 lines. The root projects forward from one of the long sides, and the enamelled surface of the scales is covered with parallel square lines.

This species is named in honor of Dr. Hayden, who collected the remains characterized in this paper; and which remains, I suspect, indicate the existence of a formation like that of the Wealden of Europe.