Found this on Usenet:
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The difference between the so-called "ji" �L or the "ba" �K
over the "mouth" are insignificant variants in the typefaces
used in modern (since 200 AD or so) books. It definitely
isn't anything to so with the "ji" mentioned in previous
posts. In the oracle bone and other archaic scripts the
character yan3 the RH side of �u (the phonetic or RH side of
the boat character in question ��

, the upper element is
much more complex, but was gradually simplified into two
strokes resembling the modern character "ba," now used for
the number eight. In the oracle bone and pre-Han script, the
upper element is part of the word for water: water that runs
down the two sides of a ravine and turns into mud. There
absolutely is no "eight" in the word, ancient or modern --
creationist wishful thinking notwithstanding -- except to
the eye of a modern reader with no understanding of the
archaic script and the generations of scribal
simplifications that brought us to the (Han-era) graphs we
see and use today. The entire discussion is totally
irrelevant to the history of the Chinese writing system. Sad
but true.