 The semicircular aperture is turned upward, obstructed by numerous lamellae and folds.In the aperture of "Anostoma", the primitive condition of the parietal armature remains, the angular, parietal and infraparietal lamellae being all present and separate.In "Anostoma" the parietal lamella is the longest while in other Odontostomini the infraparietal lamella is the longest.