108 PROVISIONAL AID TO THE STUDY OF TASMANIAN MOLUUSCA. 



Genus Hiatoxa. (610-611.) 

 Valves oval-oblong, compressed, ventral margin usually incurved 

 posteriorly, where the valves are attenuated ; broadly 

 rounded anteriorly ; beaks sub-median, not prominent, 

 violaceous, under an olive epidermis ; ligament thick, 

 swollen ; one or two very small cardinal teeth in each 

 valve; muscular impressions rounded, distant; pallial 

 impression very sinuous. Dist.—W. Indies, Eed Sea, 

 India, Madagascar, Japan, Australia, Tasmania, Peru. 



(lxxx.) Family VeneridtE. 

 (Shell regular, closed, sub-orbicular or oblong ; ligament external ; 

 hinge with usually three diverging teeth in each 

 valve; muscular impression oval, polished; pallial 

 line sinuated.) 



Genus Venus. (612-623.) 

 Shell thick, ovale, smooth, sulcated, or cancellated ; margins 

 minutely crenulated ; cardinal teeth 3-3 ; pallial sinus 

 small, angular ; ligament prominent ; lunule distinct, 

 Disl. — World-wide. Low water, 140 fathoms. V. 

 Astartoides, Behring's Sea. V. Verrucosa, Britain 

 Mediterranean, Senegal, Cape, Eed Sea, Australia ? 



Sub-Genus Chione. Megerle. (Murcta, Bomer. 

 Omphaloclathrum. Klein.) 

 Shell oval, triangular or sub-cordiform ; margins finely crenulated ; 

 hinge narrow, solid, with three teeth in the right valve, 

 two in the left, the anterior tooth longest ; ligament 

 narrow; pallial sinus shallow. Mantle-margins folded 

 and dentate ; siphons short, unequal, the branchial 

 doubly cirrated, the anal ciliated. 



Genus Cytherea. (624-631.) 

 Shell like Venus ; oval- triangular, smooth ; margins simple ; 

 hinge with three cardinal teeth and an anterior tooth 

 beneath the lunule ; pallial sinus moderate, angular. 

 Dist. — Same as Venus. Becent. 150 sp. 



Sub-Genus Callista. 

 Shell oval, transverse, inequilateral ; pallial sinus sub-oval, 

 profound. Mantle-margins folded and cirrous above 

 the siphons; siphons united, cirrated at their 

 extremities. 



Shell sub-tri 



Sub-Genus Gouldia. 

 oval, shining, inflated. 



