According to Brewer's Dictionary of Phrase and Fable:
- St. Ursula: A 5th-century British princess, according to legend, who went with 11,000 virgins on a pilgrimage to Rome and was massacred with all her companions by the Huns at Cologne. One explanation of the story is that Undecimilla (mistaken for undecim millia, 11,000) was one of Ursula's companions. (p.1119)
Somewhat appropriate name for a lemming, eh?