This bayonet has not yet been identified. 

George Moller, American Military Shoulder Arms, Volume III, states that during 1861, and in addition to the 1,000 rifles and saber bayonets purchased from Massachusetts, Maine sent 598 unaltered Model 1841 Rifles to Ames Manufacturing Company for alteration to sword bayonet.  Ames altered 595 of these rifles and returned three rifles unaltered.  Ames' alteration of these 595 rifles consisted of attaching a bayonet lug with guide key (~25 mm) to the rifles’ barrels.  It is believed that the bayonet studs used in this alteration differed slightly from the 1500 Ames had previously altered for Massachusetts by the way the lug was attached to the rifle's barrel.

Assuming that the bayonets were purchased from Ames, this bayonet has would certainly be a typical Ames style brass hilt with a smooth rib finish.  The muzzle ring inside diameter would be about 22.8 mm and the guide slot would be about 25 mm long.  Probably very similar to the Massachusetts Alteration bayonet if not identical.