Hi Ray,
Here is a record from www.rootsireland.ie/ which looks like your James. Don't be too concerned about the slight discrepancy in the year as there was a lot inaccuracy due to illiteracy or people simply not knowing their birth year.
Name:James LarkinDate of Birth:
Date of Baptism:29-Apr-1835Address:BokParish/District:BORRISOKANEGender:MaleCountyCo. Tipperary
Denomination:Roman Catholic
Father:William LarkinMother:Catherine DelanyOccupation:
Sponsor 1 /
Informant 1:Tim Hogan Sponsor 2 /
Informant 2:Mary Callenon
Did he happen to name his second daughter Catherine - that would help as, if he followed the irish naming pattern in naming his children then the second daughter would have been named after the father's mother.
Siblings:
Name:Michael LarkinDate of Birth:
Date of Baptism:20-Sep-1829Address:BokParish/District:BORRISOKANEGender:MaleCountyCo. Tipperary
Denomination:Roman Catholic
Father:William LarkinMother:Catherine Donnelly'
Name:Elizabeth LarkinDate of Birth:
Date of Baptism:13-May-1832Address:BokParish/District:BORRISOKANEGender:FemaleCountyCo. Tipperary
Denomination:Roman Catholic
Father:William LarkinMother:Catherine DonnellyOccupation:
Sponsor 1 /
Informant 1:Pat Canning Sponsor 2 /
Informant 2:Mary Renehan
I couldn't find the parents' marriage
If you search for Larkin in Tipperary in the Tithe Applotments you'll find a few Williams amongst the results (free at http://titheapplotmentbooks.nationalarchives.ie/) You might check Donnelly also to see if any were close by.
No luck in the Irish Censuses; there are no Tipperary records until 1851 & no Larkins
Col