Dorsal view of Chiton Wosnessenksii, Midd., showing the eight shells.
This circlet of gill-lamellae led Cuvier to class the limpets as Cyclobranchiata, and, by erroneous identification of them with the series of metamerically repeated ctenidia of Chiton, to associate the latter mollusc with the former.
It seems probable that it is identical with one of the open sacs in which each shell-plate of a Chiton is formed, and the series of plate-like imbrications which are placed behind the single shell-sac on the dorsum of the curious slug, Plectrophorus, suggest the possibility of the formation of a series of shellsacs on the back of that animal similar to those which we find in Chiton.
The chiton, xcrcww, was formed by sewing together at the sides two pieces of linen, or a double piece folded together, leaving spaces at the top for the arms and neck, and fastening the top edges together over the shoulders and upper arm with buttons or brooches; more rarely we find a plain sleeveless chiton.