a.  Masculine:  apex, peak; codex, tree-trunk; grex, flock; imbrex,
  tile; pollex, thumb; vertex, summit; calix, cup.

5.  Nouns in -s preceded by a consonant.

  a.  Masculine:  dens, tooth; fons, fountain; mons, mountain; pons,
  bridge.

6.  Nouns in -do.

  a.  Masculine:  cardo, hinge; ordo, order.

46.  Exceptions to the Rule for Neuters.

1.  Nouns in -l.

  a.  Masculine:  sol, sun; sal, salt.

2.  Nouns in -n.

  a.  Masculine:  pecten, comb.

3.  Nouns in -ur.

  a.  Masculine:  vultur, vulture.

4.  Nouns in -us.

  a.  Masculine:  lepus, hare.

Greek Nouns of the Third Declension.

47.  The following are the chief peculiarities of these:—­

1.  The ending -a in the Accusative Singular; as, aethera, aether; Salamina, Salamis.

2.  The ending -es in the Nominative Plural; as, Phryges, Phrygians.

3.  The ending -as in the Accusative Plural; as, Phrygas, Phrygians.

4.  Proper names in -as (Genitive -antis) have -a in the Vocative Singular; as, Atlas (Atlantis), Vocative Atla, Atlas.

5.  Neuters in -ma (Genitive -matis) have -is instead of -ibus in the Dative and Ablative Plural; as, poematis, poems.

6.  Orpheus, and other proper names ending in -eus, form the Vocative Singular in -eu (Orpheu, etc.).  But in prose the other cases usually follow the second declension; as, Orphei, Orpheo, etc.

7.  Proper names in -es, like Pericles, form the Genitive Singular sometimes in -is, sometimes in -i, as, Periclis or Pericli.

8.  Feminine proper names in -o have -us in the Genitive, but -o in the other oblique cases; as,—­

Nom.  Dido            Acc.  Dido
Gen.  Didus           Voc.  Dido
Dat.  Dido            Abl.  Dido

9.  The regular Latin endings often occur in Greek nouns.

* * * * *

FOURTH DECLENSION.

u-Stems.

48.  Nouns of the Fourth Declension end in -us Masculine, and -u Neuter.  They are declined as follows:—­

Fructus, m., fruit.              Cornu, n., horn. 
SINGULAR.        PLURAL.          SINGULAR.        PLURAL.
Nom.  fructus         fructus         cornu           cornua
Gen.  fructus         fructuum        cornus          cornuum
Dat.  fructui         fructibus       cornu           cornibus
Acc.  fructum         fructus         cornu           cornua
Voc.  fructus         fructus         cornu           cornua
Abl.  fructu          fructibus       cornu           cornibus

Peculiarities of Nouns of the Fourth Declension.