Sven.
No, they are like the ordinary GLS lamp, but the top is slightly flattened. I suppose a similar shape to the R50, but not quite so long a 'neck', and they do not have a reflector. Not very descriptive - sorry!
They were very popular in the 60's and 70's, as Paul suggests, but they are now more a decorative issue. I'm not sure why they were 'favoured', but I recall seeing an adverrt for them years ago that said they gave out more light. Lord knows how!