(1) We return to halachic discussion toward the bottom Bava Batra 75b, and the pages going forward show it, in their shape. Here is 75b:
and here is 76a:
(2) Ah, one of my favored topics, the kinyan of mesirah! You can read my full newspaper article on the subject here:
(3) Rabbi Natan was not a colleague of Rabbi Yehuda HaNasi. He is a contemporary of Rabbi Meir, and schemed with him to try to depose Rabban Shimon ben Gamliel. Rashbam says that they were colleagues:
ובפלוגתא דהני תנאי - קמיפלגי ר' נתן ורבנן דרבנן דהכא רבי ור' נתן היינו רבנן דלקמן. רבי ורבי נתן סוף משנה וחברים היו וגם אמוראי אליבייהו נינהו בהך ברייתא סתם כרבי ובאידך כר' נתן:
Pointing to the idea that Rabbi and Rabbi Natan are the close of the Mishnah. But, here is what Rav Hyman writes in Toledot Tannaim vaAmoraim.
Note that there is a Mishnat Rabbi Natan. Regarding Shmuel’s statement in Bava Metzia 86a, that Rabbi Natan and Rabbi are sof Mishnah, is that although the generation of the Sages who were Rabbi Akiva’s students were considered the Sages of the Mishnah, Rabbi Natan was not so (for he had other teachers in Bavel). So he was a colleague of Rabbi Meir, and was just like Rabbi Yoshiya and Rabbi Yonatan who don’t appear in the Mishnah.
He also notes this, on the next page:
That Seder Tannaim vaAmoraim claiming that Rabbi and Rabbi Natan were students of Rabbi Meir, that’s a scribal error, and rather they both received from Rabbi Meir.