bissextile

I refer you to Montucla, if you have any doubt about the Egyptian year being of 365 days without bissextile of any kind.

The fourth year was bissextile, and the dominical letters were F, E; the following year D, and so on.

The bissextile is known to have been used by the Mayas, Tzendals, and Quichés, and it was probably common.

Can we therefore believe that the Egyptians before this period were ignorant of the bissextile intercalation?

This fourth year was denominated Bissextile, because the sixth day before the Kalends of March was reckoned twice.