474 LASEIDiE. 



Genus LA SEA, Leach. . 



Mantle closed posteriorly ; the anterior tube-like canal 

 open below. 



Shell thin, equivalve, sub-equilateral, sub-orbicular, 

 tumid or compressed, closed, smooth or concentrically 

 striated; beaks incurved, small. Hinge composed of one 

 or two primary teeth, and a lateral tooth in both valves ; 

 ligament internal or sub-marginal, placed on a cartilage- 

 bed formed of the thickened hinge-margins of each valve. 

 Pallial sinus entire. 



Si/n. Poronia, Recluz. Cycladina, Cantr. 



Ex. L. rubra, Montagu, pi. 114, fig. 7, 7, a. Shell, L. 

 rubra, fig. 7, b, 7, c. 



The great peculiarity of Lasea is in the open, tubular 

 prolongation of the front of the mantle. The species are 

 of small size, and are found in various regions of the 

 globe. 



Species of Lasea. 



Adansonii, Cantr. purpurata, Phil. 



incerta, Recluz. rubra, Mont. 



ovata, Gould. scalaris, Phil. 



Parreysii, Phil. spurca, Recluz. 

 physoides, Lam. 



Genus KELLIA, Turton. 



A very short posterior anal siphon ; anterior tube undi- 

 vided, entire below. 



Shell thin, equivalve, sub-equilateral, sub-orbicular, 



