Discussion of place and river names ending in -σος/-σσος, accent patterns (proparoxytone/preparoxytone), doubling of sigma, gender shifts between masculine and feminine, with examples such as Telmissos, Kephisos, Ilisos, Amisos, Larisa, Molossos, etc.
πόλις Πισιδίας. τὸ μέντοι περισσός τριγενές. σεσημείωται τὸ Τελμισσός πόλις Καρίας, ὡς δὲ Φίλων καὶ Στράβων, Λυκίας. ἔστι γὰρ ἀμφοτέρων ὅριον μετὰ Δαίδαλα. Τὰ εἰς 'σος' ὑπερδισύλλαβα ἔχοντα τὴν πρὸ τέλους συλλαβὴν εἰς 'ι' ἐκτεταμένον λήγουσαν ὀξύνεται. εἰ δέ τι βεβαρυτόνηται, τοῦτο παρώνυμον ὤφθη ἀπὸ θηλυκοῦ, Κηφισός, Ἰλισός ποταμὸς τῆς Ἀττικῆς, ἐν ᾧ τιμῶνται αἱ Μοῦσαι Ἰλισίδες, ὡς Ἀπολλόδωρος. Κεδρισός, Ἀμισός πόλις ἐν Πόντῳ. λέγεται καὶ ἀρσενικῶς. Ἀμνισός ποταμὸς Κρήτης. τὸ δὲ Ἄρνισος Ἄρνισα, Λάρισος Λάρισα ἀπὸ θηλυκῶν, ὡσαύτως καὶ Μήρισος, Μάρισος ὁ ποταμός, Πάμισος, Κρίμισος ὁ ποταμὸς Σικελίας, Μόρμισος ὁ ποταμός, Νάϊσος, ὕρισος βαρύνονται. Τὰ εἰς 'σος' ὑπερδισύλλαβα τῷ 'ο' παραληγόμενα ἐν διπλασιασμῷ τοῦ 'σ' ὀξύνεται, νεοσσός, κολοσσός, Μολοσσός ὄνομα ἔθνους. Τὰ εἰς δύο 'σσ' παραληγόμενα τῷ 'υ' προπαροξύνεται, Γένυσσος ὄνομα ποταμοῦ. Ἄμφρυσσος πόλις Φωκίδος. καὶ δι´ ἑνὸς 'σ' ἐκφέρεται. τινὲς δὲ διὰ τοῦ 'β' φασί. ἔστι καὶ ποταμὸς Μαγνησίας. Ἴνυσσος πόλις Αἰγύπτου προσεχὴς τῷ Κασίῳ ὄρει. Ἡρόδοτος ( 3, 5). ὡσαύτως καὶ τὰ δι´ ἑνὸς 'σ' ἐκφερόμενα προπαροξύνεται, μέθυσος, γόγγυσος, Διόνυσος, Ὄνυσος ὁ ποταμός. ἄφυσος, ἄρυσος ἀγγεῖον πλεκτὸν σπυριδῶδες. Ἰάλυσος ἥρως καὶ πόλις ἐν Ῥόδῳ καὶ ἐν Σκυθίᾳ καὶ ἐν τῷ Ἀδρίᾳ. Ἀμφίλυσος ποταμὸς Σάμου. Εὐφορίων Ἀρτεμιδώρῳ »δαῖμον ὃς Ἀμφιλύσοιο ῥόον«. Τὰ εἰς 'σσος' ὑπὲρ δύο συλλαβὰς τῷ 'ω' παραληγόμενα ὀξύνεται, Κερωσσός πόλις Ἀπολλωνιάδος. Βηρωσσός, Κεδρωσσός ἔθνος πλησίον τῆς Ἐρυθρᾶς θαλάσσης, οὓς καὶ Γεδρωσίους καλοῦσιν. τὸ δὲ ἅλωσος ἓν 'σ' ἔχει· γέγονε δὲ παρὰ τὸν ἁλώσω μέλλοντα.
A city of Pisidia. The word περισσός, however, is of threefold origin. Telμισσός, a city of Caria, is noted; but according to Philo and Strabo, of Lycia. For it is the boundary of both, together with Daedala. Words in -σος, of more than two syllables, having the syllable before the last ending in a lengthened ι, are accented with an acute. But if any is found to be barytone, this has been seen to be a derivative from a feminine: Κηφισός, Ἰλισός, a river of Attica, in which the Muses Ἰλισίδες are honored, as Apollodorus says; Κεδρισός; Ἀμισός, a city in Pontus (it is also said in the masculine); Ἀμνισός, a river of Crete. But Ἄρνισος from Ἄρνισα, and Λάρισος from Λάρισα, are from feminines; likewise also Μήρισος, Μάρισος the river, Πάμισος, Κρίμισος the river of Sicily, Μόρμισος the river, Νάϊσος, ὕρισος are barytone. Words in -σος, of more than two syllables, with ο in the penult, when the σ is doubled, are accented with an acute: νεοσσός, κολοσσός, Μολοσσός, the name of a people. Those with two σσ and υ in the penult are proparoxytone: Γένυσσος, the name of a river; Ἄμφρυσσος, a city of Phocis (it is also pronounced with a single σ; but some say with β); there is also a river of Magnesia; Ἴνυσσος, a city of Egypt near Mount Casius—Herodotus (3, 5). Likewise also those pronounced with a single σ are proparoxytone: μέθυσος, γόγγυσος, Διόνυσος, Ὄνυσος the river; ἄφυσος; ἄρυσος, a woven vessel like a basket. Ἰάλυσος, a hero and a city in Rhodes and in Scythia and in the Adriatic; Ἀμφίλυσος, a river of Samos. Euphorion to Artemidorus: “a divinity who [is] the stream of Ἀμφίλυσος.” Words in -σσος, of more than two syllables, with ω in the penult, are accented with an acute: Κερωσσός, a city of Apolloniatis; Βηρωσσός; Κεδρωσσός, a people near the Red Sea, whom they also call Gedrosians. But ἅλωσος has one σ; and it has come from the future ἁλώσω.