Shell regularly oval, conoidal, the summit elevated, pointed, very slightly directed forward, situated at the front two-fifths of the length. From the apex radiate a great number of very fine, regular, rather equal riblets, which bear long, obtuse granules. The margins are simple and sharp. The interior lined with very bright nacre of a whitish-brown, the central callus quite large, white, sharply defined by the muscle-scar. The shell is thin, semi-transparent, of a uniform brown-blackish, but if held up toward the light, a few rays of a beautiful red become visible. Length 23-31 mm; Width 19-26 mm; Height 5-9 mm. Radula : Very similar to that of C. testudinaria, except for the lateral, which is short, broadly arched and expanded above, and very deeply notched.

The writer has seen neither the type nor a photograph of this species. The type was not available at the time of writing, owing to reorganisation of the collections of the Museum National d'Histoire Naturelle, Paris. It is not certain that the type is located in the collections of that institution.
However Deshayes excellent illustrations show a shell very similar to a common shell from northern Madagascar, the only marked difference being in the position of the apex, which is shown near central in Deshayes figures but is at about the anterior fourth or fifth in Madagascar shells. Deshayes shell is tall-conic, but the Madagascar shells are very depressed. However the position of the apex, which is to a great extent governed by the altitude of the shell, varies considerably within many species of limpets, and is therefore of little taxonomic importance. Upon the assumption that the Madagascar shells represent garconi, then that species appears to be related to the Indo-Pacific C. testudinaria and represents a western offshoot of that species, just as vitiensis (=sagitata) is an eastern outlier in the Pacific. The main differences in garconi, compared with testudinaria, are the smaller, more lightly built shell, with dense more definite sculpture, the radials being very numerous, and bearing distinct ovate granules; also the shell tends to be narrow in front, and never has the chevroned or tortoise-shell markings of testudinaria.

Island of Reunion and northern Madagascar.