the Rambam in the introduction to Mishne Torah counts 40 generations from Moshe Rabeinu to Rav Ashi (compiler of the talmud) in the transmission of the oral law and lists the names of these sages.
Are these 40 continuous generations? (i.e. one sage transmitting to another) If no, how big are the gaps between them?
excerpt from there
Thus, there were forty generations from Rav Ashi back to Moses, our teacher, of blessed memory. They were: 1) Rav Ashi [received the tradition] from Ravva. 2) Ravva [received the tradition] from Rabbah.....