The Heads of Venice

Headstone in Campo San Basegio, Venice
The keystone (chiave di volta) of an arch is also known as a headstone and in Venice, more often than not, it actually takes the form of a carved head. 

The head (at least, when it appears above the main entrance to a palazzo) is always male and almost always bearded (and invariably has a pigeon perched on top!). 

Are there any female heads guarding the entrances to Venetian palazzi?