We've reached the second round in Ultimate Classic Rock's Greatest Summer Song battle. And in this contest, Mungo Jerry's good-time hit "In the Summertime" goes up against the Beach Boys' eternal "California Girls."

After starting with 32 of classic rock’s best summertime songs last week, we're now down to 16 for the second round. Over the next four weeks the field will be repeatedly cut in half by your votes until we arrive at the greatest summer song ever made.

The Beach Boys had the bigger victory, stomping all over Sly and the Family Stone's "Hot Fun in the Summertime" with more than 78 percent of the vote in the first round. One-hit-wonders Mungo Jerry had a tougher time claiming victory over the Ramones' "Rockaway Beach," eventually triumphing with 55 percent of the vote.

"California Girls" was recorded in 1965, just a few months before the Beach Boys started work on their masterpiece Pet Sounds. Its complex opening helped spur the group in its adventurous new direction. "In the Summertime," on the other hand, was the only hit for the British band Mungo Jerry. It reached No. 3 in 1970, marking one of the few instances when a skiffle-influenced jug-band song was all over U.S. airwaves.

So which song will make it through to the semifinals? That's where you come in. We've embedded both songs below so that you can make an informed decision. You can vote once per hour in each of the eight second-round Greatest Summer Song battles until voting closes on Aug. 3 at 11:59PM ET. Your choice for the Greatest Summer Song of all time will be revealed on Aug. 25, 2015.

Watch Mungo Jerry Perform ‘In the Summertime’

Watch the Beach Boys Perform ‘California Girls’

See the Beach Boys and Other Rockers in the Top 100 Albums of the '60s