Lewis Short
Prorsa | Prōsa (noun F) : (), , 2. prorsus, sc. dea, i. e.
* The goddess presiding over births with the head foremost (opp. Postverta), Varr. ap. Gell. 16, 16, 4; cf. Hartung, Relig. d. Röm. 2, p. 199.
Charlton T. Lewis, Charles Short, A Latin Dictionary