These 'dance of death' calendars were illustrated by Louis Crucius (or Crusius). They were part of a marketing campaign targeting physicians.
According to BibliOdyssey, Antikamni Chemical Company "produced antikamnia medicines containing the coal tar derivative, acetanilid, an anti-fever drug with pain relieving properties somewhat related to paracetamol, but which would be later shown to be a toxic compound not to mention addictive. Antikamnia was mixed with substances like codeine and quinine to enhance the pain relieving effects."
For more of the story behind these calendar pages, visit BibliOdyssey.