Pictures from Portrait of a Lady

Photos courtesy of 

Eric Eldred's Hawthorne page at Eldritch Press

"Isabel saw no more of her attributive victim [Lord Warburton] for the next twenty-four hours, but on the second day after the visit to the opera she encountered him in the gallery of the Capitol, where he stood before the lion of the collection, the statue of the Dying Gladiator " (264).

This is the picture of the Dying Gaul, often misidentified as the Dying Gladiator.  For another view, go to the Dying Gaul/Dying Gladiator.. Since this statue is in the Capitoline Museum, it is probably the one referred to in Portrait of a Lady. 

For a picture of  Pierre Julien's Dying Gladiator (1779), visit this page at the Louvre 
 
Comment from Patrick Roewe (English 462, Spring 2001):
"The Dying Gaul" is the actual name, but the names have been used interchangeably throughout history.

"The Dying Gladiator" is actually a quite popular literary reference.
Besides House of Mirth, you can find it in all sorts of literary works by some very recognizable names:

Interestingly enough, there is a an actual statue called "The Dying Gladiator" by Pierre Julien created in 1779 ("The Dying Gaul" was created sometime in the 3rd century B.C.E.). It is roughly similar to "The Dying Gaul" (similar in that they are both sculptures of naked, dying men with shields and such). This statue can be viewed at:
http://www.louvre.fr/anglais/collec/sculp/rf4623/sculp_f.htm
The confusion over the names may have resulted from its use in popular literature.

Karen Reeves (English 462, Spring 2001) also points out that statues of the Dying Warrior from the west and east pediment of the Temple of Aphaia at Aegina are based on the same theme.