77-334 is an anthropomorphic dog of unknown gender.
A cousin of 47-521, 77-334 was one of the hundreds of Beagle Boys who swarmed Duckburg when they heard tell that their local relatives had finally taken control of Scrooge McDuck's fortune, wanting to get a piece of the pie. Living in Leavenworth, they drove from there to Duckburg for the occasion.
Behind the scenes
77-334 is mentioned in the 1975 comic story Scrooge For A Day. They are presumably one of the background Beagles seen later in the story, but which one is unknown.