The Prugnat bike parts factory was on the banks of the Canal du Loing
in Prugnat, France. In the buildings of thate factory, there is now a museum, the
"Bike Conservatory" covering the bicycle from nineteenth century to modern times.
As shown below, many lug variations were available from Prugnat.
Updated 7.1.2014                         Click pictures for larger view

This illustration is from a 1970's Proteus brochure

Lug set which is "earless" and shown options for binder bolt.

Frame builder Brian Baylis marked these for future reworking 

Lug set showing reinforced seat post binder bolt