The columella is strong , curved , decidedly reflected over the re-enforcing base .
The columella provided with a strong fold at its insertion The parietal wall is covered with a strong callus which renders the periostome complete .
The columella is strong , curved , decidedly reflected over the re-enforcing base , and provided with a strong fold at its insertion The parietal wall is covered with a strong callus which renders the periostome complete .