Thank you to Alvin Lederer for contributing this image of Arthur Burns "Pappy" Chalk's amphibious airline operation on Biscayne Boulevard. The aircraft are believed to be Loening C-2C Air Yachts which were manufactured starting in 1928. However, Wikipedia states that Chalk's moved their operation to Watson Island in 1926, which could very well be in error due to many other errors noted on Wikipedia.
Mr. Chalk started Chalk's Flying Service in 1919, two years after moving to Miami from Paducah, Kentucky. He had traded his mechanic skills for flying lessons from aviation legend Tony Jannus who pioneered scheduled airline service by launching a regular hop from St. Petersburg to Tampa in 1914. After serving in World War I, Chalk started his own flying service in Miami, then largely undeveloped, with a single Stinson Voyager seaplane. He charged $5 for sightseeing flights and $15 for flying lessons.
The Loening C-2C Air Yacht particulars: 1928 (ATC 90, 2-116), 525hp Wright Cyclone; span: 46'8" length: 34'8" load: 2006# v: 124/102/52 range: 550. Pilot and one passenger in an open cockpit. $27,900