This is an old trade card for a San Francisco bookseller and stationer, E.C. Thatcher and his business with the colorful name, Eureka Bazaar.
An 1888-89 Northern Pacific Coast Directory has this entry for Eureka Bazar (sic) at a different address in San Francisco (I presume, as the street address exists there today) with a different owner, a woman referred to as Mrs. Douglas:
DOUGLAS MRS E A
proprietress Eureka Bazar
Using all this information has produced not one iota of a clue about this old San Francisco bookseller, whose card I would date about 1880s. But perhaps the "C" in E.C. Thatcher stands for "Carter" and E.C. is the ancestor of the Carter Thatcher in San Francisco for whom the University of San Francisco Thatcher Gallery was named. Maybe... Just maybe...
I also hoped Janvier, noticeably displayed on the front of the card, might give me something to write about, but this apparently is the month of January, not an artist's name.
So from front to back, this trade card is one big mystery. No Eureka! moments yet.