Gorila Fight!
And without further ado...

I really can't tell you much about this fascinating item. Here's what it says in the BobCat entry:
"Thackeray is shown among the spectators in the 1st plate & perhaps assisted in drawing them."
which explains why this thing is in Fales and shelved under Thackeray. There is one full page of text, which I haven't had time to read, and four illustrations (in addition to the cover illustration shown above).
Here's the first plate:

and here's a detail of that plate:

I guess that's Mr. Thackeray in the crowd there, head and shoulders above all the other primates. What's up with that?
I leave it to you, the eager researcher, to come in to Fales to pore over this oddity of Victoriana and come up with some answers!