It is generally assumed that there was a god Fons or Fontus, to whom this day was sacred. There was a delubrum Fontis[1049]; an ara Fonti on the Janiculum[1050]; and a porta Fontinalis in the Campus Martius. Fons also appears with Flora, Mater Larum, Summanus, &c., in the ritual of the Fratres Arvales[1051]. The case seems to be one of those in which multiplicity passes into a quasi-unity: but Fons did not survive long in the latter stage. ID. OCT. (OCT. 15). NP. EQUUS AD NIXAS FIT. (PHILOC.) No calendar but the late one of Philocalus mentions the undoubtedly primitive rite of horse-sacrifice which took place on this day. Wissowa has tried to explain this difficulty, which meets us elsewhere in the Calendar, e. g. on the Ides of May (Argei), June 1 (festival of Carna)[1052]. Where two festivals fell on the same day, _both_ would not be found in calendars which were meant for the use, not of the pontifices themselves, but of the unlearned vulgar; for the latter would not be able to distinguish, or to get one clear name for the day, and confusion would result. Now all Kalends and Ides were sacred to Juno and Jupiter respectively; all other rites falling on these days would stand a chance of being omitted, unless indeed they were noticed in later annotations such as we find cut in smaller letters in the Fasti Praenestini and others. Luckily the entry in Philocalus’ calendar is supplemented sufficiently from other sources. The earliest hint we get comes from the Greek historian Timaeus, and is preserved in a fragment of the twelfth book of Polybius[1053]. Timaeus after the Greek fashion connects the horse-sacrifice with the legend of Troy and the wooden horse: but he also tells us the important detail that on a certain day _a war-horse was killed with a spear in the Campus Martius_[1054]. The passage is no doubt characteristic of Timaeus, both in regard to the detail, and the mythology which Polybius despised. But though we do not know that Timaeus was ever at Rome, we may hope that he was correct in the one particular which we do not learn from other sources, viz. the slaughter of the horse with the sacred weapon of Mars.