Mendicula Iredale, 1924

Type species. Lucina induta Hedley, 1907 = M. memorata Iredale, 1924 .

Diagnosis. Small to minute shells. Equivalve. Equilateral to slightly inequilateral with prosogyrous beaks posterior of the midline. Outline transversely ovate to subcircular, posterior area weakly demarcated by a radial angulation; submarginal sulcus long and shallow; lunule a slight depression. Hinge with an anterior tubercle or thickening that in the right valve most developed. Exteriorly most with a heavy ferruginous coating. Ctenidium of a single demibranch, foot with a developed heel, lateral body pouches with few branches.

Remarks. The above diagnosis is somewhat more restrictive than that given by Payne & Allen (1991) and would exclude species such as Thyasira (M.) carrozae Payne & Allen, 1991 where there is a well developed peg like tooth in each valve; T. (M.) ultima Payne & Allen, 1991 in which there are well developed myophoric ridges on both adductor scars and T. (M.) verrilli Payne & Allen, 1991 where there are weak myophoric lines. These species are anatomically similar to Mendicula and cannot be transferred to Thyasira . Payne & Allen (1991) do not include Adontorhina but their T. (M.) transversa Payne & Allen, 1991 should be transferred to this genus as the hinge plate has microscopic crenulations characteristic of that genus (pers. obs.)