Mantle canals. Scale bar = 1 cm (= 0.5 cm in detail pictures). (a)-(b) L. depressa lata. NRM Br134087; Klintehamn, Klinte; strong mantle canals on the extremely large alae. (c) L. depressa lata. NRM Br32745; Västergarn, Sanda; note mantle canals on the disc as well as the trail. (d) L. depressa depressa. NRM Br138045; Mulde Tegelbruk, Fröjel; Halla Formation; rare example of visible mantle canals on the ventral trail.