What kind of appetizers would be served at rich peoples parties in New York in the 1880s?

Yes, I would say definitely caviar would be served. Also,
some sort of pate de fois gras (goose liver pate). Since it is New York, there
definitely would be some type of oyster dish - either raw oysters on the half shell,
oysters Rockefeller or some other preparation. There would be crudites - raw vegetables
with a dip. There also would be some fancy type of appetizers "en croute" - which means
in a crust - perhaps meat covered in a crust and fried or baked. There would also be
various types of expensive cheeses, cured meats such as expensive salami, pancetta or
ham. Also, there would definitley be shrimp cocktail. This was very popular and would
have been readily available in New York City. There would be some other type of fish as
well, perhaps salted cod, smoked salmon, or the like. Also, I have read that sardines
were popular back then, not on pizzas but on little crackers topped with a green olive.
Another thing that rich people liked to eat were things "en gelee" - that means, encased
in a gelatin. Soft boiled eggs "en gelee" were popular. This item is a French appetizer
but things would have been imported by the rich to be served at their fancy parties.
Also, truffles - which is a type of wild mushroom found in France that can only be
uncovered by wild pigs. Weird, huh?