ses; axis, axes; basis, bases;
crisis, crises; diaeresis, diaereses; diesis, dieses; ellipsis, ellipses;
emphasis, emphases; fascis, fasces; hypothesis, hypotheses; metamorphosis,
metamorphoses; oasis, oases; parenthesis, parentheses; phasis, phases;
praxis, praxes; synopsis, synopses; synthesis, syntheses; syrtis, syrtes;
thesis, theses_. In some, however, the original plural is not so formed;
but is made by changing _is_ to _~ides_; as, _aphis, aphides; apsis,
apsides; ascaris, ascarides; bolis, bolides; cantharis, cantharides;
chrysalis, chrysalides; ephemeris, ephemerides; epidermis, epidermides_. So
_iris_ and _proboscis_, which we make regular; and perhaps some of the
foregoing may be made so too. Fisher writes _Praxises_ for _praxes_, though
not very properly. See his _Gram_, p. v. _Eques_, a Roman knight, makes
_equites_ in the plural.

5. Of nouns in _x_, there are few, if any, which ought not to form the
plural regularly, when used as English words; though the Latins changed _x_
to _ces_, and _ex_ to _ices_, making the _i_ sometimes long and sometimes
short: as, _apex, apices_, for _apexes; appendix, appendices_, for
_appendixes; calix, calices_, for _calixes_; _calx, calces_, for _calxes;
calyx, calyces_, for _calyxes; caudex, caudices_, for _caudexes; cicatrix,
cicatrices_, for _cicatrixes; helix, helices_, for _helixes; index,
indices_, for _indexes; matrix, matrices_, for _matrixes; quincunx,
quincunces_, for _quincunxes; radix, radices_, for _radixes; varix,
varices_, for _varixes; vertex, vertices_, for _vertexes; vortex,
vortices_, for _vortexes_. Some Greek words in _x_ change that letter to
_ges_; as, _larynx, larynges_, for _larinxes; phalanx, phalanges_, for
_phalanxes_. _Billet-doux_, from the French, is _billets-doux_ in the
plural.

6. Of nouns in _on_, derived from Greek, the greater part always form the
plural regularly; as, _etymons, gnomons, ichneumons, myrmidons, phlegmons,
trigons, tetragons, pentagons, hexagons, heptagons, octagons, enneagons,
decagons, hendecagons, dodecagons, polygons_. So _trihedrons, tetrahedrons,
pentahedrons_, &c., though some say, these last may end in _dra_, which I
think improper. For a few words of this class, however, there are double
plurals in use; as, _automata_ or _atomatons, criteria_ or _criterions,
parhelia_ or _parhelions_; and the plural of _phenomenon_ appears to be
always _phenomena_.

7. The plural of _legumen_ is _legumens_ or _legumina_; of _stam