(b) Nigidius Figulus[11] says that when we pronounce the word vos we gradually thrust out the ends of our lips. This remark describes perfectly the position of the mouth in pronouncing vos if we assume that v had the sound of English w.
(c) The Greek writers in transliterating Latin names generally represent consonantal v by ου; thus, Οὐαλήριος for Valerius; Οὐόλσκι for Volsci; Ιουουενάλια for Iuvenalia; Οὐᾶρος for Varus. Sometimes, to be sure, v is represented by β, but this is chiefly in Plutarch, who is a Boeotian and confesses his own ignorance of Latin[12]; or else it is done in proper names in which by using β the word becomes in appearance more like a Greek one; that is, its form becomes Hellenized: as for instance, Λίβιος, Φούλβιος etc., for Livius and Fulvius,—the termination –βιος being common in Greek.
22. X: had the sound of x in English.
The grammarians say that the character axis a monogram representing cs or gs. Quintilian remarks that x is not an indispensable letter in Latin, implying that cs and gs could take its place. In early Latin, cs was often written for x. (Max. Victor, p. 1945 P).
23. Y: had the sound of French u or German ü.
See [III], supra.
24. Z: had the sound of English z and modern Greek ζ. See [p. 12].
Z was a letter used by the Umbrians and Oscans, but it appears first in ordinary Latin about Cicero's time in the transliteration of Greek words. Before this time, ζ had been imperfectly represented in the Latin by s or ss, as sona for ζώνη, and badisso for βαδίζω. It was, in classical times, always regarded by the Romans as a Greek letter. Marius Victorinus remarks: "If z were essential to the Latin language, we should represent it by ds."
[1] Seelmann, Die Aussprache des Latein, p. 175 sqq.
[2] Quint. I. 4, 14.