A folk song widely reputed to be Irish (gracious, could that be because of the mention of Dublin in the first line?) but actually written by a Scot, James Yorkston, sometime before 1884. There are several slight changes in lyrics among versions, but nothing dramatic. It seems to me that the song may have been written in imitation of popular Irish folk songs at the time, or as a showcase for the Irish tenor: there is a dramatic sixth between the syllables of "Molly", which really encourages a showy, sustained note. However, this is conjecture; it's not as if Scotland lacks folk music.
In Dublin's fair city, where girls are so pretty
'Twas there that I first met sweet Molly Malone
As she wheeled her wheelbarrow
Through streets broad and narrow
Crying cockles and mussels, alive, alive-O!
Alive, alive-O! alive, alive-O!
Crying cockles and mussels, alive, alive-O!
She was a fishmonger, but sure 'twas no wonder
For so were her father and mother before
And they each wheeled their barrow
Through streets broad and narrow
Crying cockles and mussels, alive, alive-O!
Alive, alive-O! alive, alive-O!
Crying cockles and mussels, alive, alive-O!
She died of a fever, and no one could save her
And that was the end of sweet Molly Malone
But her ghost wheels her barrow
Through streets broad and narrow
Crying cockles and mussels, alive, alive-O!
Alive, alive-O! alive, alive-O!
Crying cockles and mussels, alive, alive-O!
Sources:
http://www.contemplator.com/folk/cockles.html
http://www.nimusic.com/f_history.html