And while we're there, you can also see the red piping on the blouse which symbolizes the fact that many of the first Marines didn't have uniforms, so they took the redcoats from the British in the Revolution, turned them wrong side out, and wore the blue lining out (with the red underenath showing a little).
If I remember correctly, the Marines were wearing green uniforms during the Revolution:

http://www.ussnicholas.org/samuel_nicholas.html

"In 1776, the Naval Committee of the Second Continental Congress prescribed new uniform regulations. Marine uniforms were to consist of green coats with buff white facings, buff breeches and black gaiters. "

-- http://www.usmcmuseum.org/Museum_LoreCorps.asp

And here is a nice article from a SAR web site about the term "Leatherneck":

http://www.southcoastsar.org/Leathernecks.htm

Regards,

Todd