When compared with the rest of the passage, the and in front of the fourth “according to the words of X” seems intrusive; thus Joseph Smith removed this extra and in his editing for the 1837 edition. If the and is maintained, the rest of the verse becomes a sentence fragment and the infinitive phrase “and to be buried in a sepulchre” is not directly assigned to a prophetic source, unlike the three preceding examples in the passage.
The importance of Zenos’s prophesying of Christ’s burial in a sepulchre is that during the period covering three days (when Christ’s body would be in the tomb), great destruction would visit the Nephites and the Lamanites. Otherwise, a prophecy about being buried in a sepulchre would not be particularly noteworthy. Thus it does seem inappropriate to have the conjunction and separate off the text referring to “the three days of darkness” from the preceding “to be buried in a sepulchre”.
It is possible that the and was accidentally inserted as Oliver Cowdery took down Joseph Smith’s dictation, especially since he had just written down two and ’s (“and to be crucified … and to be buried in a sepulchre”). In the following example from the book of Alma, we have a clear case of this tendency for Oliver to accidentally insert an extra and in the original manuscript. In this instance, the error was obvious, and thus Oliver immediately deleted the extra and:
The probable source for Oliver accidentally writing the & after “and now it came to pass” was the preceding and.
As an aside, we should note that in this one verse (1 Nephi 19:10), Oliver Cowdery may have made as many as three scribal errors as he wrote down Joseph Smith’s dictation in the original manuscript: (1) the skipping of the God in “and the God of Isaac”, (2) the omission of the word up from “yieldeth himself up”, and (3) the addition of an extra and before “according to the words of Zenos”.
Summary: Accept Joseph Smith’s emendation of 1 Nephi 19:10 (namely, his removal of the conjunction and after sepulchre) as the probable reading of the original text; such an emendation maintains the parallelism of the text, prevents a following sentence fragment, and connects the period of time in the sepulchre with Zenos’s prophecy about the three days of darkness.