LEPTON. 79 



a curiously tubular elongation, communicating by open edges 



with the foot in front. The shell of 



K. niticla is white, rather square, and flat, with one very 



sharp cardinal and two broad lateral teeth in each 



valve ; 

 K. sulorUculans, yellowish, similar in form, with a partly 



internal ligament, no cardinal teeth, two short lateral 



teeth in one valve ; 

 K. rubra, very minute, tinged with red, rounded in front, 



squarish behind, hinge nearly as in K. suhorhicularis. 

 The KeUi(B, sometimes among rocks and shells and some- 

 times hiding under seaweeds, sometimes attached by their 

 byssus and at other times free, have doubtless their own 

 means of enjoyment unobserved in their quiet retreats. 



lY. Lepton is so called from the square, flat, scale-Yike 

 form of its small, white shell. The following extracts from 

 Mr. Alder's account of the animal will be read with plea- 

 sure. 



" When lately dredging in Towley's harbour, I fortunately 

 met with a living individual of this rare genus, the Lepton 

 squamosum, which I kept alive for a fortnight, and am thus 

 enabled to supply some account of its characters and habits. 

 It is of a transparent white, the mantle is very large, and 



