Billionaires row, just South of Mar-a-Lago and Southern Blvd. (Sheet 27) and North of Widener's curve (Sheet 31)

Several interesting early property owner names on this sheet

Francis P. Bolton was married to Chester Bolton and served for 14 terms in the United States House of Representatives in Ohio

Millicent V. Hearst - wife of Randolph Hearst

According to Wikipedia Alice DeLamar was the lesbian heiress to Joseph Raphael De Lamar. She was a relatively important supporter of the arts, helping fund plays by Mercedes de Acosta. DeLamar also donated some of her land in Palm Beach, Florida to the Audubon Society in the 1960s

Louis J. Horowitzr - Built many of New York Cities skyscrapers in the early 1900's

Sheet 30 small low res scan

Lake Worth to the Atlantic Ocean

The two little islands in Lake Worth could be spoil islands indicating the digging of a channel leading to the Bolton Estate

It's my best guess that most of the regular pencil markups found in the atlas were made in the late 1940's. On the few sheets that have red pencil markups, like this one, that they were made a couple decades later