On p. 5:237, "Vital Records of Marshfield, Mass.", "Marriage by Mr Edward Tompson": John Blackmer and Anna Br[a]nch were Married [worn]er ye 19 : 1700.
On p. 32:121, "The Will of John Branch of Marshfield, it states: "Anna Branch, married, 18 September, 1700, John Blackmer".
[Despite George Bowman's excellent reputation as a transcriber, December seems to be the correct interpretation, since both on p. 5:237, and in S1, the list of marriages by Edward Tompson appears to be arranged chronologically, and this entry follows another marriage on 11 Dec 1700.]