Sentence:  Pioneer seemed now to have the game in his own hands; but the Captain, by taking two desperate leaps, cut off a corner, by which he regained the ground he had lost by the fall, and was up with the <WSD>grey</WSD> the remainder of the chase. 
Meaning of the word marked with <WSD> tags:  An animal or thing of grey colour, such as a horse, badger, or salmon.