93. Case Endings. These are given in the following table. The endings of the consonantal declension are in larger type: the two vowel declensions of nouns are numbered (1), (2), and the pronominal declension (3).
94. Stems ending in ι, υ, and σ are liable to lose the final letter before the case endings which begin with a vowel.
- Stems in -ηυ, -ευ: e.g. νηῦ-ς, genitive νη-ός (for νηϝ-ός), rarely νε-ός. The ε arises by shortening from η; so νέες, νεῶν, νέεσσι, νέας—all less common than the corresponding forms with η-, νῆες, νηῶν, νήεσσι, νῆας.
The forms νηῦ-ς, νηυ-σί are irregular, since original ᾱυ before a consonant would appear in Greek as ᾰυ (cp. Ζεύς for original dyēus). Hence the true Greek form is preserved in the instrumental ναῦ-φιν (§ 104) and the compounds ναυσι-κλυτός, Ναυσι-κάα, etc. The η of νηῦ-ς and νηυ-σί is taken by analogy from the other cases. βασιλεύ-ς, genitive. βασιλῆ-ος (but dative plural βασιλεῦ-σι) 
 Πηλεύ-ς, genitive Πηλῆ-ος and Πηλέ-οςIn oblique cases of stems in -ευ the ε seems to be nearly confined to proper names. Τυδέος, Τυδέϊ, Τυδέα 
 Ἀτρέος, Ἀτρέϊ
 Θησέα
 Νηλέα, etc.On Ζεύς, βοῦς see § 106.2. 
- Stems in -ι and -υ form the same cases in two ways
 (1) Retaining the stem vowel κόνι-ς, κόνι-ος 
 Πάρι-ς, Πάρι-ος
 ἰλύς ,ἰλῦος
 ἰχθύ-ς ,ἰχθύ-ες
 σῦ-ς, συ-ός, συ-ί, σύ-εςIt is probable that this form of declension was originally confined to monosyllables. (2) Inserting ε and dropping ι or υ. πόσι-ς, dative πόσε-ϊ 
 ἄστυ, ἄστε-ος
 πῆχυ-ς, πήχε-ος
 πολύ-ς ,πολέ-οςHere the stem of the oblique cases ends in -ει, -ευ; henc genitive -εος for -ει-ος, -εϝ-ος, etc. πόλις forms several of its cases in three ways. (1) genitive πόλι-ος, dative πόλῑ (for πόλι-ι, § 99) 
 plural nominative πόλι-ες, genitive πολί-ων, dative πολί-εσσι, accusative πόλι-ας and πόλῑς (§ 100).(2) genitive πόλεος (so Bekk. reads in Il. 2.811, Il. 21.567, with the scanning ˘ ¯; cp. πόλευς in Theognis), dative πόλει, πτόλεϊ (Il. 17.152, perhaps should be πτόλιι, cp. the Cyprian form πτολιyι). (3) genitive πόλη-ος, dative πόλη-ϊ 
 plural nominative πόλη-ες, accusative πόλη-ας.The stem πολη- which furnishes the last of these three forms of inflection has been traced by Joh. Schmidt (K Z. xxvii. p. 287) to a primitive locative in -η (cp. Sanskrit agni, Loc. agnā), to which the ordinary locative -ῐ was suffixed. From this new locative πόλη-ϊ the other cases were then formed by analogy. The nouns in -ᾰ (from -ι̯ᾰ) answer to the original stems in ῑ, as ἰδυῖα, for ἰδυσ-ι̯α, Sanskrit vidush-ī. ἠΰ-ς or ἐΰ-ς good makes genitive ἐῆ-ος, perhaps by transference of quantity for ἠέ-ος. Other adjectives in -ύς form -έ-ος, -έ-ι, etc. 
- Stems in -εσ, -ασ, -οσ drop the σ, as ἔπε-ος, κέρα-ος, αἰδό-ος.
95. Original ᾱ as the final vowel of the stem becomes η; except
- after ε, ει, ᾰ, as in θεά, and the proper names Ἑρμείας, Αἰνείας, Αὐγείας, Ναυσικάα, Ῥεία (Ar. on Il. 14. 203), Φειά (Il. 7.135, Od. 15.297), and
- in the genitive in -ᾱο and -ᾱων.
Other exceptions to the scheme given above will be best treated under the separate cases.
