nervex was a company that made widgets for the bicycle frame industry.
they were also called etablissents aime dubois. their catalog included
hundreds of lug types, and other small parts, for all types of bicycles.
the ref 49 and the ref 32 are the most well known here in the lower 48.

here are some pics and links atmo:
http://www.veloworks.com/lug_referen...ery/index.html
http://www.richardsachs.com/articles/rsachscrown.html
http://www.richardsachs.com/articles/rsachslugs.html
http://www.richardsachs.com/articles/rsachslug1.html