2. That it has a relation to the number of meanings belonging to the words: thus, when a single word has two meanings, the original inflexion expresses one, the English inflexion another—genius, genii, often (spirits), geniuses (men of genius).

3. That it occurs with substantives only, and that only in the expression of number. Thus, although the plural of substantives like axis and genius are Latin, the possessive cases are English. So also are the degrees of comparison, for

adjectives like circular, and the tenses, &c. for verbs, like perambulate.

[§ 159]. The following is a list of the chief Latin substantives, introduced during the latter part of the fourth period; and, preserving the Latin plural forms—

FIRST CLASS.

Words wherein the Latin Plural is the same as the Latin Singular.

(a) Sing. Plur.
Apparatus apparatus
Hiatus hiatus
Impetus impetus.
(b) Sing. Plur.
Caries caries
Congeries congeries
Series series
Species species
Superficies superficies.

SECOND CLASS.

Words wherein the Latin Plural is formed from the Latin Singular by changing the last Syllable.

(a).—Where the Singular termination -a is changed in the Plural into :—