Nonius Marcellus was a Latin lexicographer and grammarian of the late 3rd century AD whose book is important as both an ancient work on linguistics and also a rich source of quotations from otherwise lost works and authors. Nettleship here provides an extended introduction and commentary to this important and difficult author, including an extensive section of notes. Although it provides little in the way of translation assistance, it will be a good companion for an advanced reader of the Latin text and an excellent introduction to this important but little-known author for anyone wishing to learn more about him.