Gekielde Arianta?

The author collected some decades ago a specimen of Arianta arbustorum that was deposited in a private collection and reported to be carinate. He does not know of any references in the malacological literature to carination of the shell of this species and urges malacologists to look for carinate specimens in their collection and in individual-rich populations of Arianta and among the snail shells, in thrush forges. The question is posed what posSible use or advantage shell carination might have.