Lituites marshi (Hall, 1867) ammonoid fossil found in Louisville, Kentucky USA. It dates to the Silurian Period and was probably found in the Louisville Limestone. This image is from the 1889 Kentucky Fossil Shells by Henry Nettelroth in Plate XXX figure 1. "Found in the Niagara rocks of the quarries east of the city of Louisville, where fragments of this shell are not rare, but fair specimens are not often found. In the speciment illustrated on plate 30, both termini of the shell are missing; it has preserved more than three complete volutions. The vacant central space indicates that, probably, two full volutions are obliterated there at the apex. How much there is destroyed at the other end can not be acertained, but that there is a large part of a volution missing can not be doubted. Thus it appears that the illustrated specimen, in its perfect condition, had six full volutions." Professor James Hall (1811-1898) named this species in honor of Professor Othniel Charles Marsh (1831-1899).
This fossil is stored at the Smithsonian and was assigned catalog number: USNM PAL 51378.
Here is a posting from 2009 of one of these fossils found in Louisville:
https://louisvillefossils.blogspot.com/2009/05/silurian-coiled-cephalopod-lituites.html