Your horn is a fascinating New England horn [faceted throat, soft wood plug, sea images] with intriguing artwork. My thoughts come from someone who has "dabbled" in scrimshaw over the years but not deeply. I doubt the carver was ever on a whaling vessel and probably had never seen an actual whale, but he lived close enough to the whaling area that he heard all the stories... and tried to show a whaling "adventure" on the horn. Had he been a whaler, the depictions of the whales would have been significantly different, more like an actual whale [probably flatter nose, larger tail, fewer but larger fins], instead of just oversized fish. The mermaid holding a comb for her hair was a common theme, although this one "almost" looks like it started out as another whale, and the carver suddenly decided he would rather have a mermaid on the horn so rethought the emerging whale.
I may be a bit off, but when I see a strongly New England horn like this, but with a more rounded butt plug and some inland figures mixed in such as the long vine and various birds, I think the horn was made farther inland, away from the coast, where hunting was more important. They used whale oil as most New Englander did, but weren't near to, or actively involved in whaling... just knew it was an important industry that represented New England to most Americans. Perhaps he made the horn for a retired sailor who wanted to remember his glory days whaling on the endless oceans, but the old salt couldn't accurately describe what whales and whaling scenes looked like... but got close and left the carver to work from second-hand knowledge.
Despite not being signed, the carving is too good to be the only horn the carver ever made, which makes me believe it was a semi-professional horn made for someone else.
Shelby Gallien