Just a little ride to C.I.
I'm pretty sure Papa's Coney Island companion on this day was a new character named Blanche, though I might be reading the name wrong (the "a" after the "l" doesn't look exactly like his usual "a," but I can't think of what else it might be):
Whatever her name might be, I wonder who she is and how Papa met her. Could she be "Miss R.," the "American girl" who expressed her affection for him a couple of days ago? He said he planned to take her out, and he often did his romancing on public transportation trips like train or ferry rides to Coney Island. He certainly would have been happy to be among the couples strolling the boardwalk rather than wistfully observing them from afar, as he has done in the past.
On the other hand, Papa said he planned to take Miss R. to a concert, and this entry seems a bit brief and offhand for a description of such a potentially important date. The phrase "just a little ride to C.I." could indicate the jaunty cheerfulness of someone who's had a great time with a new gal and can't be bothered to describe it right now, or it could literally mean that his trip to Coney with Blanche was nothing remarkable. We've never met Blanche before, but since Papa's diary isn't a novel it often introduces his well-known acquaintances without ceremony, as it recently did with Clara II. Is Blanche just an old friend?