Mary Ann Shirley was born 1 Nov 1855 in Aghadowey Parish, the tenth child and youngest child of Valentine Shirley and Ann Orr. Mary Ann traveled to the U.S. with her mother in the early 1870s, arriving presumably in Philadelphia. She married John S. Quigg, who was also born in Ireland. First they lived in Catasauqua, Pennsylvania, and then Indiana.
I think the middle initial stands for Samuel. He was born about 1852 possibly in Aghadowey Parish in Londonderry close to Coleraine, Ireland. His brother was Robert John, James, William, Samuel, Thomas and sister, Elizabeth.