Original Description of Strombus williamsi by Olsson & Petit, 1964, p. 561:
- "The shell is large, shaped like S. gigas but differing in the weaker development of the shoulder spines which in the type specimen are present only on the shoulder of the penultimate whorl and the whorl above, lacking from the earlier spire whorls and on the back and final portion of the body whorl. The spire is broad, forming a low, nearly straight-sided cone, except for the short spinelike nodes of the penultimate and preceding whorl, the suture fine, appressed against the shoulder above, undulated around the shoulder nodes where these are present. Surface of the spire whorls is marked with low spiral cords, heaviest on the upperhalf, hardly developed in the lower section and over the shoulder nodes. Main surface or that of the body whorl below the shoulder is covered with low spiral cords which in the type show a tendency towards a weak banding, in groups of three, four or more. Outer lip expanded, produced a little above, its outer edge somewhat thickened, not showing any definite stromboid notch. Parietal wall covered by a coat of callus."
Stratum typicum: "Pinecrest beds, Brighton facies", Tamiami Fm., late Pliocene
Locus typicus: "Indian reservation levee", Florida, USA
Types: Holotype: Smithsonian Institution USNM 644660
Dimensions: "Length 230 mm., diameter 155 mm."
Strombus williamsi Olsson & Petit, 1964, pl. 81, fig. 6
Specimens from institutional collections
Lobatus williamsi (Olsson & Petit, 1964); Pleistocene; Griffin Brothers quarry, 10 km east of Miami Canal, along Broward-Palm Beach County line, Florida, USA; Coll. Stichting Schepsel Schelp no. SSS 35467
Specimens from private collections
Lobatus williamsi (Olsson & Petit, 1964); Florida, USA; Coll. Chris Newman
Lobatus williamsi (Olsson & Petit, 1964); late Pleistocene; Lee County, Florida, USA; Coll. Gijs Kronenberg no. 6335
Lobatus williamsi (Olsson & Petit, 1964); Bermont Formation, middle Pleistocene; Griffin Brothers quarry, 10 km east of Miami Canal, along Broward-Palm Beach County line, Florida, USA; Coll. Ralf Buchsot
- Landau, B. M., Kronenberg, G. C., & Herbert, G. S. (2008). A large new species of Lobatus (Gastropoda: Strombidae) from the Neogene of the Dominican Republic, with notes on the genus. The Veliger, 50(1), 31-38.
- A.A. Olsson & R.E. Petit. 1964. Some Neogene Mollusca from Florida and the Carolinas. Part 1. The Geology and Stratigraphy of South Florida. Part 2. Paleontology and systematic treatment. Bulletins of American Paleontology 47(217): 509-575
- Petuch E.J. & Drolshagen M. (2011) Compendium of Florida fossil shells, volume 1. Wellington, Florida: MdM Publishing. 412 pp.