The Rock-Scraping Radula, a Striking Case of Convergence (Mollusca)

In nine subfamilies, belonging to four superfamilies of the order Stylommatophora (Mollusca, Gastropoda), radulae are found in which series of uniform cusps, without side cusps, occupy at least the middle of the transverse rows. This type of specialized radula has only been encountered in species living on rock-faces; it is called the rock-scraping radula. A rock-scraping radula is found to be at most a character of generic value. Higher taxa for which it is typical are not known.