[Qgis-user] bessel ellipsoid 1841

[Torsten Lange]

Hello,

I have a historical map from 1855 from the Muensterland Basin, Germany. The 
map shows geographic coordinates, thus my colleague said most likely it's 
Bessel 1841 ellipsoid.

QGis offers:
Unknown datum based upon the Bessel 1841 ellipsoid EPSG:4004
+proj=longlat +ellps=bessel +no_defs

Why there is no datum? Shouldn't there be one?

Thank you, Torsten