I believe that #18 is my ancestral cousin, Audrey Munson. She was a famous nude model who is the basis for several statues in NYC. She lived from June 8, 1891 – February 20, 1996, but spent the last two thirds of her life in an institution. There are a few similar photos of her on record taken in an artist's studio. Artists study skeletons for the purposes of learning human anatomy. Audrey Munson on wikipedia