Sepulcrum artifis ignoti

I saw this phrase, which translates as "the tomb of the unknown artist", on a postcard the other day.  The picture on the card was of a piece by the artist Grayson Perry.  The work of art was not my taste, however the phrase caught my eye, because it illustrated a simple grammatical observation.

As every student of Latin knows, an adjective must agree with its noun in number, gender and case.  As a consequence the ending on nouns and their accompanying adjectives are quite often the same.  For example, puella pulchra meaning beautiful girl.  However, whilst adjectives must always agree with their nouns, the actual ending expessing this need not be the same.

In the phrase "sepulcrum artifis ignoti", artifis is the genitive singular of a third declension masculine noun artifex, artifis, whilst ignoti is the genitive singular masculine of a second declension adjective ignotus, -a, -um.   Thus although the two words still agree, their ending are different.