Printed on the plate
“Hybrid Grouse”
Tetrao hybridus
Engraved caption: Hybrid Grouse Tetrao hybridus (Sparrm.)
This identification is still open; the reasoning below says what would settle it. If you can, open an issue with the evidence.
Modern identification
Not identified
Why
Tetrao hybridus is the Rackelhahn, a hybrid Western Capercaillie x Black Grouse, as Gould himself says. No single species to name.
Sources
General List (vol. I); engraved caption; Gould's text; Sharpe, Cat. Birds BM xxii; the plate
Who made the plate
No credit line could be read. Credit lines cut off: the sheet ends in the caption.