Mulligan says that he stole his shaving mirror from "the skivvy's room" in his parents' house. "Skivvy" is British slang for a female servant who does menial domestic labor like housecleaning—not far from the role of dogsbody that Mulligan has just assigned to Stephen. To the injury of stealing possessions from this very poor woman, Mulligan adds an insult about her looks and behavior: "The aunt always keeps plainlooking servants for Malachi. Lead him not into temptation. And her name is Ursula." Ursula was a 3rd century Christian martyr passionately devoted to virginity.
Thornton notes the relevant fact that Alban Butler's Lives of the Saints (New York, 1846) proclaimed that Ursula "is regarded as a model and patroness by those who undertake to train up youth in the sentiments and practice of piety and religion." Unsurprisingly, Mulligan would prefer not to be trained up.
According to legend, the Cornish princess Ursula recruited 11,000 virgins to undertake a pilgrimage around Europe promoting virginity; and, supposedly, the Huns slaughtered all of them at Cologne. Scholars have speculated that, if the legend was based on any history at all, the truly impressive number of dispatched virgins probably derived from a misreading, in the 9th century, of historical records from the 5th century that mentioned anywhere from two to eleven martyrs. One possibility is that XI. M. V., referring to eleven martyred virgins, was misread as eleven thousand virgins, since M is the Roman symbol for 1,000. In Cyclops, when Martin Cunningham's remark, "God bless all here is my prayer," conjures up a hoard of "mitred abbots and priors and guardians and monks and friars," the bloated procession concludes with the appearance of "S. Ursula with eleven thousand virgins."