Pitman's Commercial Spanish Grammar (2nd ed.)

1. Words of Greek etymology ending in ma --

El dilema (the dilemma)
El diploma (the diploma)
El epigrama (the epigram)
El problema (the problem)
El síntoma (the symptom)
El telegrama (the telegram)

etc., etc.

But La amalgama (the amalgamation)
La diadema (the diadem)
La estratagema (the stratagem)
La proclama (the proclamation)

2. Most of the compound nouns (very few in number) --

El cortaplumas (the penknife)
El guardacosta (the coasting-vessel)
El paraguas (the umbrella)
El tirabala (the popgun)

3. El día (the day)

El Etna (Etna (volcano))
El mapa (the map)
El sofá (the sofa)
El Volga [210] (the Volga)
And all words ending in accented a.

Footnote 210: And all rivers and mountains ending in a.

4. Masculine nouns ending in d --

El adalid (the warrior or chieftain)
El ardid (the trick)
El ataúd (coffin)
El césped (the turf, lawn)
El sud (the south)

5. Masculine nouns ending in ión --

El embrión (the embryo)
El gorrión (the sparrow)
El morrión (parts of an armor)
El sarampión (measles)

6. Feminine nouns ending in i or y --

La diócesi (the diocese)
La grey (the flock)
La ley (the law)
La metrópoli (the metropolis)

Almost all.

7. Feminine noun ending in j --
La troj (the granary)

8. Feminine nouns ending in l --

La cal (lime)
La capital (capital -- town)
La cárcel (prison)
La col (cabbage)
La miel (honey)
La piel (skin)
La sal (salt)
La señal (signal)
La vocal (vowel)

And a few more.

9. Feminine nouns ending in n --

La cargazón (the load)
La crin (the horsehair)
La desazón (the ailment)
La imagen (the image)
La razón (the reason)
La sinrazón (the injustice)
La sartén (the frying-pan)
La sien (the temple)

Almost all.

10. Feminine nouns ending in o --

La mano (the hand)

Only word, excepting "nao" (ship), now obsolete, and "seo" (cathedral), little used.

11. Feminine nouns ending in r --

La flor (the flower)
La labor (the needlework)
La segur (the axe)

Almost all.

12. Feminine nouns ending in s --

La bilis (the bile)
La crisis (the crisis)
La elipsis (ellipsis)
La lis (fleur-de-lis)
La mies (the crop)
La perífrasis (the periphrase)
La tos (the cough)

And a few others.

13. Feminine noun ending in u --

La tribu (the tribe)

14. Feminine nouns ending in z --

La codorniz (the partridge)
La cerviz (the cervix)
La cruz (the cross)
La coz (the back-kick)
La luz (the light)
La nariz (the nose)
La nuez (the nut)
La pez (the pitch)
La voz (the voice)
La raíz (the root)
La tez (the complexion)
La vez (the time, once, etc., etc.)

And a few others less important.

15. Feminine nouns ending in e. (This is the most numerous list of exceptions) --

Las aves (the birds)
La barbarie (the barbarity)
La base (the basis)
La calle (the street)
La carne (the flesh)
La fiebre (the fever)
La fuente (the fountain)
El hambre (f.), (the hunger)
La mente (the mind)
La noche (the night)
La parte (the part)
La quiete (the quiet)
La sangre (the blood)
La serpiente (the serpent)
La torre (the tower)