From the parish records of St. Patrick Church, Montreal:
The sixth(?) August 1879, after the publication of banns....William Lawrence McKenna, a commercial traveller, domiciled in this parish, son of age of deceased Francis(?) McKenna and Mary O'Brien of County Tyrone in Ireland, married Teresa Adelaide Brennan, domiciled in this parish, daughter of age of deceased Francis Brennan, merchant, and Johanna Heffernan, of this parish; witnesses: Pierre Belanger, Frank Brennan, J. O'Brien, Frank Rochford.
Teresa signed her own name as Theresa.
Son, Francis Ethelbert McKenna, baptized 19 December 1882, born 16 December.
Son, Joseph Edward Reginald McKenna, baptized 4 September 1889, born 29 August.
Daughter, Marie Irene McKenna, baptized 3 December 1884, born 29 November.
Son, William Francis McKenna, baptized 7 April 1881, born 12 instant (which usually means the same month), but a mistake must have been made and the child was born on 12 March.
1881 Canadian Census St. Antoine Ward, Montreal
McKenna, J.L., aged 28, born Ireland, commercial traveller, married McKenna, Theresa, aged 24, born United States, married McKenna, William, aged 11 months (born March), born Quebec
Next door: Brennan, Johanna, aged 65, born Ireland, Catholic, widow
Johanna died in Montreal in 1888 -- image is hard to read to give you an exact date.