Here's the original caption, from the Smithsonian Archive:
Description: Artists in costume at the Sherwood Studio Building. Identification on front (handwritten): Sherwood Studio Bldg. 58 W 57th St. 1889. (from left to right): Wm. Allen, Sullivant, Robt. Reid, Robt. Van Boskerck, Willard Metcalf, Sam Isham, Harry W. Watrous, Carleton Chapman, Herbert Denman. Published in: Archives of American Art Journal v. 9, no. 2, p. 7; v. 15, no. 1, p. 8; v. 36, no. 3-4, p.13
I confess- I've never heard of any of these guys. Doesn't matter though, you just know they're artists.
I went to art school, then worked in comic books for awhile, and we never got dressed up like this. The comic book artist community would have been far more likely to wear outlandish get-ups than the oh- so- serious Art Students, but neither group did. At least not when I was there. People at comic conventions dressed in costumes, but they weren't artists. In any non- pretentious sensible use of the word.