The photo is of three Yale students, c. 1883, which I found courtesy of Staci’s blog, Passing Interest, where she notes that:
A Yale dean ruled that no member of the Yale Dramatic Association could impersonate a female on stage for more than two consecutive years ‘because continued impersonation tended to make men effeminate.'”
Slippery slope, indeed.
You can find more history of crossdressing at Yale at the Larry Kramer Initiative site. I recommend reading the whole of these archives of LGBT history at Yale, but if you don’t have time to read the whole thing, do at least check out the entry about two trans Yale alums.