Length of i in radix
The Elem. Lewis (which you can view online at http://www.perseus.tufts.edu/hopper/morph?l=radix&la=la#lexicon) suggests that the i in radix is actually long. On the other hand, L&S leaves the i unmarked, but I suspect that this is because the reader is expected to know that -ix always has long i, whereas the length of the a is not obvious (compare duco, which is listed dūco there). Shouldn't the entry be edited to reflect this?