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This curious shell was discovered by Montagu, and 

 described by him from a single valve. Although quite 

 aware that it did not belong to any of the Linnean 

 genera, he was much more averse than naturalists of the 

 present day to travel out of the beaten path, and he 

 therefore provisionally placed it in Solen. Its shape is 

 not very dissimilar from that of a Solenicurtus. Its 

 nearest comparison, however, would be to a fish-scale ; 

 and its sculpture is equally beautiful, and resembles the 

 finest Jace laid out on cambric. The pit-marks which 

 cover the surface of the shell are like those which ladies 

 so often see on the top of their thimbles, but without 

 admiring or noticing the ornamentation, their thoughts 

 perhaps being occupied with something else. The re- 

 fraction of light through the punctures makes the silver- 

 white shell appear under a microscope to be studded 

 with glittering dew-drops. Nor is the animal less 

 curious or lovely than the shell. Two excellent ob- 

 servers, Alder and Clark, have published some interesting 

 details of its peculiarities and habits. Mr. Alder says 

 that the single filament noticed in my description is 

 waved to and fro like a tentacle when the animal is 

 crawling, and apparently enables it to feel its way as it 

 goes. The other filaments are comparatively motionless, 

 floating loosely in the water, though capable of being 

 thrown out or withdrawn at pleasure. The edges of its 

 large foot can be either closed or expanded so as to 

 form a disk, as in Nucula. As may be imagined from 

 the size of the foot, the Lepton crawls about very freely ; 

 and sometimes it swims in an inverted position on the 

 under surface of the water, in the manner of some Gas- 

 teropods, the hinder part of the foot being then unfolded 

 and disk-shape ; but its favourite posture is that of 

 repose, suspended perpendicularly, with the beaks of its 



