In all these words the c of the singular number is sounded as k, of the plural as s.
[§ 160]. The following is a list of the chief Greek substantives lately introduced, and preserving the Greek plural forms—
FIRST CLASS.
Words where the singular termination -on is changed in the plural into -a:—
| Sing. Plur. Aphelion aphelia Perihelion perihelia Automaton automata | Sing. Plur. Criterion criteria Ephemeron ephemera Phænomenon phænomena. |
| Sing. | Plur. |
| Aphelion | aphelia |
| Perihelion | perihelia |
| Automaton | automata |
| Sing. | Plur. |
| Criterion | criteria |
| Ephemeron | ephemera |
| Phænomenon | phænomena. |
SECOND CLASS.
Words where the plural is formed from the original root by adding either -es or -a, but where the singular rejects the last letter of the original root.
Plurals in -es:—
| Original root. | Plur. | Sing. |
| Apsid- | apsides | apsis |
| Cantharid- | cantharides | cantharis |
| Chrysalid- | chrysalides | chrysalis |
| Ephemerid- | ephemerides | ephemeris |
| Tripod- | tripodes | tripos. |