[variaga]

That's correct, the Romans had March as the first month of the year, so leap day was the last day of the year and September, October, November and December were the 7th (sept), 8th (oct), ninth (nov) and 10th (dec) months.

[ljsprague]

June and July used to be Quintilis and Sextilis.

[quesera]

I think Quintilis and Sextilis were renamed to July and August, in honor of Julius and Augustus, respectively.