Arms
Coat of Arms of the O'Dowd Clan
O'Hart records two arms for the O'Dowd Clan. One in what is today County Mayo (the senior branch) and the other in Sligo.

Princes of Hy-Fiachra (Mayo)[1]
ARMS - Vert a saltire or, in chief two swords in saltire, points upwards, the dexter surmounted of the sinister argent, pommels and hilts gold.
CREST - over a coronet, a dexter hand in armour, holding a dart, proper.
SUPPORTERS - two lions rampant
MOTTO - "Virtus Ipsa Suis Firmissima Nititur Armis" (Bravery is Best Sustained by Arms).

Princes of Hy-Fiachra (Sligo)[2]
ARMS - or a saltier sable, in chief two swords in saltier, points upwards, the dexter surmounted of the sinister argent, pommels and hilts gold, in base and oak leaf, the stalk upwards, vert.
CREST - over a coronet, a dexter hand in armour, holding a dart, proper.
SUPPORTERS - two lions rampant
MOTTO - "Virtus Ipsa Suis Firmissima Nititur Armis" (Bravery is Best Sustained by Arms).

Source:
http://en.wikipedia.org/wiki/O


^ "Irish pedigrees: or, The origin and stem of the Irish nation, volume 1" by John O'Hart (page 650), James Duffy and Co. Limited, 5th Edition, 1892.
^ "Irish pedigrees: or, The origin and stem of the Irish nation, volume 2" by John O'Hart (page 329), James Duffy and Co. Limited, 5th Edition, 1892.
"The O'Dubhda Family History" By Conor MacHale, Clan O'Dowd Historian, Inniscrone, 1990.
"The Royal New Zealand Fencibles 1847 - 1852," ISBN 0-473-04716-0, Ruth Alexander, Alan la Roche, Gail Gibson. The New Zealand Fencible Society (Inc), 1997. O'Dowd family papers.