In memory of twin sons
of Richard and Mary
died June 10 1872
You cannot see the bottom line in the photo. According to the transcription of the monument by the Bruce Grey Branch Ontario Genealogical Society Badjeros Union Cemetery (Osprey Township Grey County) the last line is
age 2 days.
I was not able to find neither birth nor death information doing a search on Ancestry.ca using different variables for these unnamed twin boys.