I think it was Mart who posted this site on AA. http://www.roma-victrix.com/armamentarium/loricae_muscolate.htm
If that Samnite breastplate is 30cm high, that would make it about 11 1/4" or slightly more at the chest.

[ Linked Image ]
A soldier from the Roman Republic during the Punic Wars. I believe that the equipment carried by every Roman Republic soldier varies accordingly.

Since nobody has posted primary-source imagery of unarmoured Romans, I suppose it'd do no harm to put these up from the triumphal arch in Orange even though they're a little late for the Republic:

http://upload.wikimedia.org/wikipedia/commons...taglia.jpg

http://upload.wikimedia.org/wikipedia/commons...tonord.jpg

Here's the access to Polybius' Histories (Left - Polybius' original in ancient Greek; right - N. D. Triandafyllopoulos' modern Greek translation):
http://www.greek-language.gr/Resources/ancien...ature/part

I got a 404 Not Found error on that page, but Perseus has it.

http://www.perseus.tufts.edu/hopper/text?doc=...99.01.0233

The phrase is ἁλυσιδωτοὺς θώρακας (halusidotos thorax) [6.23.15], which means something like "armour wrought in chain fashion", which sounds like mail to me. As Elliot said, the passage certainly suggests that mail was expensive - only those with a qualification above ten thousand drachmas (μυρίας δραχμὰς) were required to wear it. It was definitely more expensive than the bronze καρδιοφύλαξ ("heart protector") that the other soldiers were required to wear.