Passage lists coastal peoples and place-names along a maritime circuit (e.g., Κύνητες, Ταρτήσιοι, Ῥοδανός), mentions several cities and rivers named Ἴς/Ἲς and Θίς/Φθίς, and then discusses phonological/accentual behavior of monosyllables ending in -ις (changes like -ιν → -ις, example pairs, rare occurrences) and scholarly opinions (Aristarchus, Aischrion) about accentuation and perispasis.
τὰ παράλια τοῦ διάπλου, διώρισται ὀνόμασιν ἓν γένος ἐὸν κατὰ φῦλα· πρῶτον μὲν οἱ ἐπὶ τοῖς ἐσχάτοις οἰκέοντες τὰ πρὸς δυσμέων Κύνητες ὀνομάζονται, ἀπ´ ἐκείνων δὲ ἤδη πρὸς βορέην ἰόντι Γλῆτες, μετὰ δὲ Ταρτήσιοι, μετὰ δὲ Ἐλβυσίνιοι, μετὰ δὲ Μαστιηνοί, μετὰ δὲ Κελκιανοί, ἔπειτα δὲ ἤδη ὁ Ῥοδανός«. Τλής ἔθνος Ἰβηρικὸν περιοικοῦν τοὺς Ταρτησσίους. Θεόπομπος τεσσαρακοστῷ πέμπτῳ. Κλής ἐπὶ τοῦ ποταμοῦ, Ζής παρὰ Φερεκύδει κατὰ κίνησιν ἰδίαν, θής ὁ μίσθιος, βλής »νύμφα φίλη, καὶ βλητὶ λίθῳ ἐνὶ δάκρυον ἧκας«. περισπᾶται δὲ τὰ ἰσοσύλλαβα Δρῆς Τρῆς κύρια. ὡς δέ τινες βούλονται, καὶ τὸ Ζῆς. * Τὰ εἰς 'ις' μονοσύλλαβα φύσει εἰς 'ς' λήγοντα ὀξύνεται ὁμοίως τοῖς εἰς 'ιν' τροπὴν τοῦ 'ν' εἰς 'ς' ἀναδεξαμένοις οἷον ἴν ἴς, ῥίν ῥίς. εἰσὶ δὲ σπάνια. Ἴς πόλις Περσική. Ἡρόδοτος πρώτῃ (c. 179)· ἔνθα καὶ ποταμὸς Ἴς οὕτω καὶ Σκύμνος ἐν τῷ ιʹ τῆς Ἀσίας περίπλῳ παρέθετο· »ἔχεται Κελένδερις πόλις Σαμίων, καὶ ἱερὸν παρὰ τῇ πόλει Ἥρης καὶ ἄλσος· Ἲς ποταμὸς παρὰ θάλασσαν ἔξεισιν«. Ἔστιν Ἴς τῆς Ἰταλίας, ὡς Πάρθαξ ἐν τῷ βʹ τῶν Ἰταλικῶν. »Ἐπεὶ δὲ ἀφίκετο εἰς τὴν Ποσειδωνίαν ὁ Ἡρακλῆς. ἔστι δὲ ποταμὸς Ἲς καλούμενος μέγας«. Θίς πόλις Αἰγυπτία πλησίον Ἀβύδου. Φθίς· Φθῖες γὰρ καὶ Φθῖοι οἱ Φθιῶται. κίς ὁ σκώληξ. λίς ὁ λέων. τοῦτο δὲ ὁ μὲν Ἀρίσταρχος ὀξύνει· ὁ δὲ Αἰσχρίων περισπᾷ, ὡς γὰρ παρὰ τὸ μῦς μῦν φησὶ καὶ νοῦς νοῦν, οὕτω καὶ λῖς λῖν »ἐπί τε λῖν ἤγαγε δαίμων« (Λ 480). καὶ ἔστι συγκατατίθεσθαι τῷ Αἰσχρίωνι, ὅτι μᾶλλον ὀφείλει περισπᾶσθαι, εἰ καὶ μηδὲν τῶν εἰς 'ις' ληγόντων καὶ ἀρσενικὸν γένος ὑπισχουμένων περιεσπάσθη. καὶ τάχα καθ´ ἕτερον λόγον, ἵνα τὸ ἐπιθετικὸν καὶ σημαῖνον γένος θηλυκὸν καὶ ὀξυνόμενον ἀποφύγῃ. λέγω δὲ τὸ »λὶς πέτρη« (Od. μ 64). τῷ μέντοι χαρακτῆρι τοῦ κίς καὶ θίς καὶ ῥίς, καίτοιγε διαφόρως κλιθεῖσι πρὸς τὸ λίς, συνεξωμοίωσεν αὐτὸ κατὰ τόνον ὁ Ἀρίσταρχος. καὶ οὕτως ἐπείσθη ἡ παράδοσις. τίς, ὅπερ συστέλλει τὸ 'ι', Δίς ὁ Ζεύς παρὰ Ῥίνθωνι.
The coastal regions of the crossing are distinguished by names, being one stock according to tribes: first, those dwelling at the farthest limits toward the west are called Κύνητες; from them, as one goes now toward the north, Γλῆτες, then Ταρτήσιοι, then Ἐλβυσίνιοι, then Μαστιηνοί, then Κελκιανοί, and then already the Ῥοδανός.” Τλῆς: an Iberian people dwelling around the Ταρτήσιοι. Theopompus in the forty-fifth book. Κλῆς: on the river. Ζῆς in Pherecydes, according to a special movement; θῆς, “the hired man”; βλῆς: “dear nymph, and with a βλητὸς stone thou didst bring a tear within.” The proper names Δρῆς, Τρῆς, being isosyllabic, take the circumflex; and, as some wish, Ζῆς as well.
The monosyllables in -ις, by nature ending in -ς, are accented with an acute, like those in -ιν that have admitted a change of ν to ς, e.g. ἴν, ἴς; ῥίν, ῥίς. They are, however, rare. Ἴς, a Persian city: Herodotus in the first book (c. 179): where there is also a river Ἴς; thus too Scymnus in the tenth book of the Periplus of Asia cited it: “Next is Κελένδερις, a city of the Samians, and a sanctuary of Hera by the city and a grove; the river Ἴς flows out by the sea.” There is an Ἴς of Italy, as Parthax in the second book of the Italica: “And when Heracles came to Poseidonia: there is also a great river called Ἴς.” Θίς, an Egyptian city near Abydos. Φθίς: for the Φθιῶται are also Φθῖες and Φθῖοι. κίς, the worm. λίς, the lion. This Aristarchus accents with an acute; but Aischrion gives it the circumflex, for, he says, just as from μῦς comes μῦν and from νοῦς comes νοῦν, so also from λῖς comes λῖν: “and a god led him against a λῖν” (Λ 480). And one may agree with Aischrion, that it ought rather to take the circumflex, even though none of those ending in -ις and professing masculine gender has been circumflexed; and perhaps for another reason, in order to avoid the adjectival form, signifying feminine gender and accented with an acute—I mean “λὶς πέτρη” (Od. μ 64). Yet, by the pattern of κίς and θίς and ῥίς, though they are declined differently from λίς, Aristarchus assimilated it to them in respect of accent; and thus the tradition was persuaded. τίς, which shortens the ι; Δίς, Zeus, in Rhinthon.