"Hidden mothers" photos. In the 1800's, mothers would take photos with their children on their laps. The mothers were often wrapped in fabric. Some of the mothers were later cropped out of the photos with mattes or frames.→[More:]
A Flickr
pool of these photos, plus
an example of how the photos would be cropped (making them much less weird looking). I'm sure this was done because early cameras had very long exposure times, and there'd be no other way to keep a baby still long enough to take the photo.