Moxon, Mechanick Excercises, 1683. Doesn’t refer to the curve parts of the letters, and most of his terms relate to the activity of punchcutting. He does however coin the term, ‘beak’ to cover the ‘fine Stroak or Touch that stands to the Left Hand of the Stem, [...] yet gs have Beaks on the Right Side of the Stem.
Thorp, in the Monotype Recorder, 1931: ‘The roman l.c. g gives more scope for variety than any other roman l.c. letter, and is generally an identifying letter of any fount. It will be found convenient, then, to distinguish explicitly four parts of the lower case g – the bowl, the link, the loop and the ear.’
‘The bowl is the name given to the upper rounded form of the g’ [...] a loose term to include the oval as well the circular’. To the parts of the tail, Thorp gives the name of link and loop, regardless of whether it is open or closed. Thus, Thorp considers he has a nomenclature ‘of sufficient explicitness’. Here are some of his descriptions:
Centaur g. Large biassed bowl; sharp-angled link horizontal; flat loop; vertical-sheared ear
Baskerville g. Flattened horizontal stressed bowl; link horizontal; curved ear; pear terminal. (The terminal here refers to the terminal resulting from the open bowl)
Garamond g. A large bowl; horizontal stressed, acute-angled link, slightly oblique; small curved, ‘blob’ ear, appreciably below mean-line.Gaskell, A nomenclature for the letterforms of roman type, 1974. The bowl is ‘a curved stroke enclosing the area’; the ear, a small stroke to the right of the bowl; the link, the middle stroke joining the bowl to the tail; the tail, the parts below the baseline of g.
More detail needed, for a proper discussion...