This cute pink cotton swim suit by Lanz Originals is from the early 1960's. It has several features that help to create the fitted silhouette. It was cut with a bodice that has princess seamlines. Each has been boned to help the bodice stay in place. The front buttons are faux, since there is a metal zipper in the back.
The bottom shorts also have princess seamlines (in the back) that help to shape the fit. These are cut with darts in the front. Because cotton shorts can't be cut to fit skin tight like a knit, there are simple cotton bloomers as lining (for modesty).
California fashion with the Lanz brand was a high end junior label that was most popular in the post WWII era through the late 1960's. The company was mostly a dress line known for its simple silhouettes in Swiss cotton prints that were accented by trims such as ric-rack, piping, bows, velvet ribbon and rows of tiny buttons (most often covered to match). Their sportswear tended to carry over the dress quality into sport garments like this swimsuit.
The details seen in this swimsuit are identical to the dresses that this label produced, including the tiny buttons, piped seamlines and the pastel cotton mini-print. It is likely that a white cotton shirt was included as a coverup.
This dress maker style of swimwear was popular throughout the 1940's, 50's and early 60's when many suits were made from woven cotton fabrics. This swim suit is fully lined in white cotton, which will prevent 'show through' while swimming, and keep the seam lines from unraveling later. The fitted and boned bodice would keep the figure looking fashonably trim as well, whether wet or dry.
Here are some views that show the details more clearly.
