"Diameter of bullae" excludes the paroccipital process and was taken from the anteriormost part of a tympanic bulla, posterolaterally to the part of that same bulla, that is exposed at the lateral side of the base of the paroccipital process.
"Mammals Obtained by Dr. Curt von Wedel from the Barrier Beach of Tamaulipas, Mexico"
E. Raymond Hall
He made his triumph for this on the Ides of October, leading, among the rest of his many captives, the general of the Veientes, an elderly man, but who had not, it seemed, acted with the prudence of age; whence even now, in sacrifices for victories, they lead an old man through the market place to the Capitol, appareled in purple, with a bulla, or child's toy, tied to it, and the crier cries, Sardians to be sold; for the Tuscans are said to be a colony of the Sardians, and the Veientes are a city of Tuscany.
"Plutarch-Lives-of-the-noble-Grecians-and-Romans"
Clough, Arthur Hugh
20, and his 'Roman Questions,' Part 3, in which he explains what the bulla is.
"Plutarch's Lives Volume III."
Plutarch