The incident happened at the end of normal time in the first half. The Exiles' flanker, Simon Fenn, remained lying on the ground following a scrum clutching his left ear. The referee, Ashley Rowden, did not see what happened but said afterwards: "There is no way it was a boot because there is a bit taken out of his lobe. It had to be a bite. There was a lot of blood. Looking at the ear it was similar to the Evander Holyfield incident when Mike Tyson bit his ear.
"I did not see who did it, But it is the worst and most heinous crime in rugby. I've never come across it before. I called the Bath captain Andy Nicol over and told him it was quite clearly a bite and that if I saw anyone else going in with their teeth they would be sent off."
Fenn, an Australian from Manly making his debut for London Scottish, was taken to hospital after the game and both clubs were said to be having a meeting about the incident. Neither would make any comment until they have thrashed things out. It is not clear whether Scottish will be able to cite a player because Rowden awarded a penalty against Bath, although logic dictates that since no one player was singled out then the culprit went unpunished.
After their abject display there is little doubt that Bath's coach, Andy Robinson, will have something to say about the rest of Bath's game. There is certainly plenty to ponder with the Heineken European Cup final looming just three weeks away.
While Scottish fought - literally at times - tooth and nail to reach the fifth round, Bath looked out of it. There was not a single phase of the game where they looked like asserting their obvious supremacy.
The Exiles were not cowed by Bath's awesome Cup reputation. They may have won the competition 10 times in 14 years, but on this showing there is little likelihood of themlifting the trophy this time.
There were patches of purple play from them, notably wing Mike Kayson's first-half try and Richard Webster's just after the interval, and of course Jon Callard's boot kept them in the the game throughout, but for the bulk of the game they were patchy. It was Scottish who lived in their faces, particularly in the close encounters.
Mick Watson did appear to be lucky to stay on when he was penalised for a high tackle after an hour, since he had been shown the yellow card for illegal footwork on Matt Perry in the second minute. But he still did a lot of great work putting in.
In fact the defence was astoundingly good. Scottish took the lead early on through a Paul Johnstone try, regained the lead through the boot of Derrick Lee, another Exile hero, lost it once more as Bath hit back then lifted everyone's spirits with a great try for their superb scrum-half, Colin Morley. Lee's boot and a penalty from Iain McAusland had Bath wobbling.
Typically Scottish lost the match in injury time when the left wing Conan Sharman was deemed to have obstructed Bath's full-back Jon Callard. The former England player slotted home the penalty. Even so Bath still had to hold out for almost nine minutes of added time before they could celebrate their victory.
Bath: J Callard; M Kayson, M Perry, M Catt (P de Glanville, 40), A Adebayo (I Balshaw, 51); R Butland, A Nicol (capt); K Yates, F Mendez (A Long, 52), V Ubogu (J Mallett, 75), N Redman, G Llanes, N Thomas, D Lyle, R Earnshaw (R Webster, 40).
London Scottish: D Lee; G Thompson, J Bonney, R Davies, C Sharman; I McAusland, C Morley (S Cook, 80); P Johnstone, J Allan (G French, 65), J Kelly (P Burnell, 40), R Hunter, M Watson, S Fenn (T Davies, 65), C Tarbuck, S Holmes (capt).
Referee: A Rowden (Reading).