Sentence:  A "volute" is a kind of spiral scroll, used in the Ionic and Composite capitals, of which it makes the principal characteristic and ornament. ... There are several diversities practised in the volute. In some, the <WSD>list</WSD> or edge, throughout all the circumvolutions, is in the same line or plane. ... [I]n others, the canal or one circumvolution is detached from the <WSD>list</WSD> of another by a vacuity or aperture. 
Meaning of the word marked with <WSD> tags:  A little square moulding; a fillet or listel.