4.  Final o is regularly long, but is short:—­

  a) In ego, duo, modo (only), cito.

  b) Rarely in the First Person Singular of the Verb, and in Nominatives of
  the Third Declension; as, amo, leo.

  c) In a few compounds beginning with the Preposition pro, especially
  before f; as profundere, proficisci, profugere.

5.  Final u is always long.

B.  Final Syllables ending in a Consonant.

364. 1.  Final syllables ending in any other consonant than s are short.  The following words, however, have a long vowel:  sal, sol, Lar, par, ver, fur, dic, duc, en, non, quin, sin, sic, cur.  Also the adverbs hic, illic, istic.[60]

2.  Final syllables in -as are long; as, terras, amas.

3.  Final syllables in -es are regularly long, but are short:—­

a) In the Nominative and Vocative Singular of dental stems (Sec. 33) of the Third Declension which have a short penult in the Genitive; as, seges (segetis), obses (obsidis), miles, dives.  But a few have -es; viz. pes, aries, abies, paries.

  b) In es (thou art), penes.

4.  Final -os is usually long, but short in os (ossis), compos, impos.

5.  Final -is is usually short, but is long:—­

  a) In Plurals; as, portis, hortis, nobis, vobis, nubis (Acc.).

  b) In the Second Person Singular Perfect Subjunctive Active; as,
  amaveris, monueris, audiveris, etc.  Yet occasional exceptions occur.

  c) In the Second Person Singular Present Indicative Active of the Fourth
  Conjugation; as, audis.

  d) In vis, force; is, thou goest; fis; sis; velis; nolis; vis, thou
  wilt (mavis, quamvis, quivis, etc.).

6.  Final -us is usually short, but is long:—­

  a) In the Genitive Singular and in the Nominative, Accusative, and
  Vocative Plural of the Fourth Declension; as, fructus.

  b) In the Nominative and Vocative Singular of those nouns of the Third
  Declension in which the u belongs to the stem; as, palus (-udis),
  servitus (-utis), tellus (-uris).

365.  Greek Nouns retain in Latin their original quantity; as, Aenea, epitome, Delos, Pallas, Simois, Salamis, Didus, Paridi, aer, aether, crater, heroas.  Yet Greek nouns in -omega-rho (-or) regularly shorten the vowel of the final syllable; as, rhetor, Hector.

VERSE-STRUCTURE.

GENERAL PRINCIPLES.

366. 1.  The metrical unit in versification is a short syllable, technically called a mora ( v ).  A long syllable ( _ ) is regarded as equivalent to two morae.

2.  A Foot is a group of syllables.  The following are the most important kinds of fundamental feet:—­

FEET OF THREE MORAE.     FEET OF FOUR MORAE.
_ v Trochee.            _ v v Dactyl.
v _ Iambus.             v v _ Anapaest.

3.  A Verse is a succession of feet.