Are both "en espèces" and "par espèces" considered correct?
According to the Larousse online dictionary,
En espèces, en argent liquide (par opposition à par chèque ou avec une carte de crédit).
However, I have heard French people say "par espèces", and on a receipt it is also written this way:
According to Google Ngram Viewer, the version with "en" is much more common in books than the version with "par":
Maybe it is becoming common to use "par" for all forms of payment, such as "par espèces", "par carte", and "par chèque"?