διὰ νήσων τὸν πλόον ἐποιεῦντο → they kept sailing through the islands
Porrĭma: ae, f.,I a Roman goddess worshipped by women, perh. another name for Carmentis, Ov. F. 1, 633; cf. Hartung, Rel. d. Röm. 2, p. 199.