SILIQUARIA. 347 



Sub-gen. azor, Gray. 



Shell, with the surface of the valves smooth, and covered 

 with an epidermis. 



coarctata, Gmel. 



Genus SILIQUARIA, Schumacher. 



Siphons elongated, cylindrical. 



Shell transversely greatly elongated, covered with an epi- 

 dermis, gaping and rounded at each end, beaks sub-central. 

 Hinge teeth 2, 3. Sinus of pallial impression very deep, 

 extending beyond the umbo. 



Syn. Tagelus, Gray. Macha, Gray, not Oken. ? Lacon- 

 silla, Baf. 



Ex. S. gibba, Spengler, pi. 93, fig. 5, 5, a. 

 8. gibba, Spengler (or S. Caribcea, Lamarck), occurs in 

 countless myriads on the bars of American rivers, in the mud 

 of which it forms cylindrical cavities, exposed at low-water 

 mark. Novaculifia is found in the mud of river- estuaries 

 in India and China. 



Species of Siliquaria. 



gibba, Spengl. Quoyi, Desk. 



media, Soiv. 



Sub-gen. novaculina, Benson. 



Beaks sub-posterior ; siphonal inflection deep, but not extend- 

 y as far as the umbo. 



acuminata, Hartley. bidentata, Spengl. 



