104 PROVISIONAL AID TO THE STUDY OF TASMANIAN MOLLUSCA. 



(lxx.) Family Teredid^e. 

 Genus Teredo. (567.) 

 Shell globular, open in front and behind, lodged at the inner 

 extremity of a burrow partly or entirely lined with shell; 

 valves three lobed, concentrically striated, and with one 

 transverse furrow ; hinge margins reflected in front, 

 marked by the anterior muscular impressions; 

 umbonal cavity with a long, curved, muscular process. 

 DisL— Norway, Britain, Black Sea, Tropics, Australasia. 

 119 fathoms. 



(lxxi.) Family Pholadidte. 



Genus Barnea. (568.) 



Shell oval, oblong, anteriorly gaping; with a single lanceolate 

 dorsal accessory valve ; umbonal process reflected, closely 

 applied. Bist. — Australia, Burmah, Eed Sea, Europe, 

 Patagonia, Philippines. 



(lxxii.) Family Solentd^. 



Genus Solen. (569.) 



Shell very long, sub-cylindrical, straight, margins parallel, ends 

 gaping ; beaks terminal, or sub-central ; hinge teeth, 

 one in each valve; ligament long, external; anterior 

 muscular impression elongated; posterior oblono'; 

 pallial line extending beyond the adductors; sinus 

 short and square. Dist. — World-wide, except Arctic 

 Seas; 100 fathoms. 



(lxxiii.) Family SAXiCAviDiE. 



Shell equivalve, thick, gaping at the extremities ; hinge with a 

 single cardinal tooth ; ligament external, prominent, 

 solid, inserted in a nymphal callosity ; pallial im- 

 pression irregular, sinuous. 



Genus Saxicava. (570.) 

 Shell when young symmetrical, with two minute teeth in each 

 valve ; adult rugose, toothless ; oblong, equivalve 

 gaping ; ligament external ; pallial line sinuated, not 

 continuous. Dist. — Universal. 



Genus Panop^a. (571.) 



Shell equivalve, thick, oblong, gaping at each end, ligament 

 external on prominent ridges ; one prominent tooth in 

 each valve ; pallial sinus deep. Dist.— Northern Seas, 

 Mediterranean, Cape, Australia, New Zealand, Pata- 

 gonia ; low water — 90 fathoms. 



