[dwcnnnghm]

I had believed something similar. They are definitely remnants of a 10 month calendar, but July and August were existing months (Quintilis and Sextilis, respectively) renamed for the emperors. January and February appear to be the additions [0]. There is quite a bit of interesting history in the rest of that article about how the months have changed.

I can't remember if I'd read about a past society that did this, or it was an idea someone had proposed for a future one, but I love the idea of a 360 day year (12 months, 30 days each), with a 5 or 6 (leap year) day festival at the end commemorating the New Year. It would change birthdays for everyone born after January 30, which seems like it'd cause enough outrage to prevent it, but it's a fun thought!

[0] https://en.wikipedia.org/wiki/Roman_calendar#Legendary_10-mo...