Type B Engraver's Die Proofs: the Proof below show a small size cardboard in comparison to that above and exhibit both the artist's signatures (designer: P. Lengellé; engraver: Jules Piel).
Besides it concerns Bichromatic Die Proofs (blue + ultramarine blue). 
 
 

Enlarged detail of the figure above.
 

Designer: De Joux;  engraver: Claude Jumelet.

fig. E52