Lavud... What if you have a gap of less than 3 tefachim in the middle of the schach? Specifically, if your sukkah is larger than the minimum. Which leads to a discussion of the purity issues of a sukkah in this way, and the absolute heritage of how impurity works in this kind of case. Note the methodology here, in terms of seeking halakhic parallels (or not, as this case may be). Also, a couple of statements by R. Yehudah bar Ilai, including one about small kosher fish - where they can be eaten, and where not.