I agree, Chris. The registration date translates to 5 June 1875 – Parcel 9, corresponding to a bundle of 2 design registrations – RD 291873 and RD 291874.
Both Thompson and Cottle describe RD 298173 as a butter dish, and RD 291874 as an ice pail.
What I think hegeman shows is indeed a RD 291873 butter. A covered version appears as Sowerby pattern 1110 on page 5 of Sowerby pattern book XI (1885). Shown as a registered design.
There is also a pattern 1110 sugar bowl on page 48 of the same pattern book, but the body appears taller and rounder than the butter dish , and the rim decoration is vertical (rather than flared or horizontal). Also shown as a registered design.
See my photos below for the matching pattern 1110 creamer, which has the same registration date lozenge, but does not appear in the pattern book.
From the Sowerby pattern book XI (1885), there is an ice pail, pattern 1109, shown on page 33 (as a registered design) that I suspect is probably the RD 291874 ice pail.
If Paul S. happens along, he may well have the design representation for RD 291873 and/or RD 291874 as confirmation.
Fred.