I found an announcement in this newspaper:
Freeman's Journal and Daily Commercial Advertiser (Dublin, Ireland), Thursday, July 15, 1830
"Old Established Stone and Marble Yard,
138, Dorset-Street, Dublin"
In this announcement, James Pettigrue stated he was assuming ownership of this business at 138 Dorset-street, Upper, previously owned by his late father-in-law, Robert McCartney.
Two of James' sons had daughters named Euphemia McCartney, so the name of Euphemia for the elder James' wife is a strong possibility. In fact, there is a gravesite with a James and Euphemia Pettigrue. I learned of this thanks to another rootschat poster.
http://www.igp-web.com/IGPArchives/#gsc.tab=0Euphemia Pettigrue d. 26 Mar 1864, aged 61.
James Pettigrue, her husband, d. 3 Feb 1882, aged 89.
Anna P. Pettigrue, their daughter, d. 18 Dec 1886. (aged 58)
Annabella Pettigrue, fourth daughter, d. 13 Apr 1912, aged 75.
In addition, civil registration records have the following siblings:
Euphemia Pettigrue d. 11 Aug 1897, Kilkee, Co. Clare, aged 64.
Thomas Perseverance Pettigrue d. 6 Apr 1922, aged 77.
Other siblings were:
Mary Pettigrue Ballantine, death details unknown.
James Justin Pettigrue d. 1915 Sherbrooke, Quebec, Canada.
http://www.willcalendars.nationalarchives.ie/reels/cwa/005014910/005014910_00206.pdfPettigrue, Euphemia, 13 Sept 1897. Probate of the will of Euphemia Pettigrue late of 31 Catherine-street Limerick Spinster who died 11 Aug 1897 at Arran View Kilkee granted to Thomas Pettigrue of Ardbraccan Navan Co. Meath Esquire. Effect L529.