by Nicolas Lancret, c. 1735
If anything strikes you as strange about these shepherdesses and the shepherd, you're right. The delicate, pointed shoes... the almost translucent lawn apron... the fine fabrics...
This scene either depicts members of the nobility at one of their favourite pastimes - playing shepherds in Arcadia - or it is a fictional scene depicting what the nobility liked to imagine shepherd life to be like. In any case, we can assume that this is how they would have dressed up when they wanted to play shepherds:
The dresses consist of separate skirts and bodices, sometimes worn with aprons. The men dress up in breeches held with bows at the knees and short jackets, also with bows.
Other examples of shepherd costume - much more elaborate - can be seen on Marquise de Pompadour, Mme Bergeret, and Countess Howe.