200 KELLIID^E. 



occupies the broader side of the shell, contrary to what 

 is the usual rule in bivalves and even in this genus, taking 

 L. squamosum as the type. His remark seems to be 

 confirmed by the position of the cartilage in the present 

 species being different from that in L. squamosum. The 

 characteristic sculpture of L. nitidum is extremely varia- 

 ble, but never absent. In apparently the smoothest and 

 most glossy specimens the pit-marks may always be 

 discerned near the beaks oculo bene armato. In all 

 probability Dr. Turton had not used a microscope when 

 he described the shell to be without punctures. From 

 this state to that of the variety convexa the gradations 

 of sculpture are almost endless. The pit-marks usually 

 are circular, but sometimes they are oval, elliptical, 

 or polygonal, and occasionally they are confluent and 

 form undulating wrinkles towards the front margin. 

 Not unfrequently one half only, or a greater or less por- 

 tion, of the surface is thus marked, the other part being 

 quite smooth. Perhaps the most elegant kind of orna- 

 mentation is that which combines the impressions exhi- 

 bited by the first variety with the radiating lines of the 

 second. The shell may readily be distinguished from 

 the young of the last species by being much less com- 

 pressed and comparatively more solid, by its beaks and 

 hinge-line being more prominent, and the teeth in- 

 finitely stronger and more compact. Mr. Clark says 

 that it is a far more active creature than L. squamosum, 

 creeping up a glass as easily as a Gasteropod ; the shell 

 is generally carried on one side, with the foot in the 

 same position, but is sometimes held upright when the 

 animal is on the march. This little gelatinous mol- 

 lusk, enclosed in its pellucid valves, 



" A liquid prisoner, pent in walls of glass," 



and having the borders of its cloak fringed with tufted 



