This corresponds to the usual presence (in the Rhynchobdellidae) of three annuli to each segment.
But in that group (Cystobranchus) there may be as many as eight annuli.
Abdomen black, consisting of seven annuli or rings, besides the tail part, the last of which is edged with orange.
This phrase is somewhat obscure: "annuli ferrei sicut solebat fieri in cista Norensi."
An eye-like spot in the Wings of many Lepidoptera, consisting of annuli of different colours, inclosing a central spot or pupil.
As remarked, the prevalent number of annuli to a segment is three in the Rhynchobdellidae.
annulus an·nu·lus or an·u·lus (ān'yə-ləs)
n. pl. an·nu·lus·es or an·nu·li (-lī')
A circular or ring-shaped structure.
Plural annuluses or annuli (ān'yə-lī')