Apex _sounded_ apec-_s_ apic_es_ Appendix -- appendic-_s_ appendic_es_ Calix -- calic-_s_ calic_es_ Cicatrix -- cicatric-_s_ cicatric_es_ Helix -- helic-_s_ helic_es_ Index -- indec-_s_ indic_es_ Radix -- radic-_s_ radic_es_ Vertex -- vertec-_s_ vertic_es_ Vortex -- vortec-_s_ vortic_es_. In all these words the _c_ of the singular number is sounded as _k_, of the plural as _s_. 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._ Apheli_on_ apheli_a_ Periheli_on_ periheli_a_ Automat_on_ automat_a_ Criteri_on_ criteri_a_ Ephemer_on_ ephemer_a_ Phaenomen_on_ phaenomen_a_. {105} 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- apsid_es_ apsis Cantharid- cantharid_es_ cantharis Chrysalid- chrysalid_es_ chrysalis Ephemerid- ephemerid_es_ ephemeris Tripod- tripod_es_ tripos. _Plurals in_ -a:-- _Original root._ _Plur._ _Sing._ Dogmat- dogmat_a_ dogma Lemmat- lemmat_a_ lemma Miasmat- miasmat_a_ miasma[23] s. 161. _Miscellaneous elements._--Of miscellaneous elements we have two sorts; those that are incorporated in our language, and are currently understood (_e.g._, the Spanish word _sherry_, the Arabic word _alkali_, and the Persian word _turban_), and those that, even amongst the educated, are considered strangers. Of this latter kind (amongst many others) are the Oriental words _hummum_, _kaftan_, _gul_, &c. Of the currently understood miscellaneous elements of the English language, the most important are from the French; some of which agree with those of the Latin of the fourth period, and the Greek in preserving the _French_ plural forms--as _beau_, _beaux_, _billets-doux_. _Italian._--Some words of Italian origin do the same: as _virtuoso_, _virtuosi_. _Hebrew._--The Hebrew words, _cherub_ and _seraph_ do the same; the form _cherub-im_, and _seraph-im_, being not only plurals but Hebrew plurals. Beyond the words derived from these five languages, none form their plurals other than after the English method, _i.e._, in _-s_: as _waltzes_, from the German word _waltz_.