We have no direct evidence of this, but we may infer it from the analogous case of Dius Fidius:—"Qui per Dium Fidium iurare vult, prodire solet in compluvium."—Non. Marc., p. 494, quoting Varro. The temples of Dius Fidius had a hole specially made in the roof ("perforatum tectum," Varro, L. L. v. 66), under which one might swear. Probably the temples of Hercules were similarly provided; certainly those of Terminus were ("exiguum templi tecta foramen habent."—Ov. F. ii. 672).
Reifferscheid, in the Annali dell' Instituto for 1867, p. 352 ff., identifies Hercules with the genius Jovis. But, in the first place, this seems to me the wrong inference from his own facts, which all have exclusively to do with the genii virorum. Next, the genius Jovis is not known before B.C. 58. Schwegler, before Reifferscheid, noticed that in Gellius, xi. 6. 1, "der römische Hercules erscheint als identisch mit dem genius der Männer."—R. G., i. 367 n.
Roscher's arguments to show that Juno is the moon are not satisfactory. He assumes without proof that Juno was always Lucina (whereas Lucina was an independent spirit worshipped in woods, Lexikon, pp. 583 and 602), that Lucina was the moon (whereas she is the spirit that brings children to light, and is not = Luna), that the Italians connected the moon with child-birth (which, as Birt says, lacks proof), that the name Juno indicates a light-giving deity (whereas, though from the root *Div, it does not imply the giving of light any more than deus does, which is applied to the di manes, the di indigetes, dea bona, dea dia, &c.). The arguments drawn by Roscher from works of art are untrustworthy, because borrowing is specially probable in their case. Finally, the hypothesis of a Græco-Italian period, on which Roscher relies to prove that Juno = Hera = the moon, is now discredited.
In B.C. 361 an Aius Locutius was produced (Liv. v. 32. 6, 50. 6, 52. 11); in 211 a Rediculus Tutanus (Festus s.v.); in or after 269 a spirit of silver coin, Argentinus (August., C. D. iv. 21 and 28); but no spirit was forthcoming for gold coin, which was first struck in B.C. 217. See further Roscher's Lexikon, s.v. Indigitamenta.
So called "quod marem effuso semine liberat."—Augustin, C. D. vii. 2.