KELLIA. 91 



crevice of a rock or the cavity of a shell, its locomotion is 

 almost limited to a half-circular turn on one of its sides ; but 

 when free, it is capable of considerable change of place, 

 aided by its strap-shaped foot, crawling forwards, back- 

 wards, or sideways, indifferently, — " especially " as Mr. Al- 

 der observes, " when it is ascending a perpendicular surface, 

 which it frequently does, for the purpose of suspending 

 itself by its byssus. The byssal aperture is about half way 

 up the foot, on the posterior surface, from which the animal 

 produces a very delicate thread, and suspends itself freely 

 by a single, almost inconspicuous fibre, strengthened by a 

 double attachment at the top." Mr. Clark informs us, 

 that though Kellia suborbicularis appears to be oviparous, 

 the point admits of doubt, for he has observed a speci- 

 men containing a completely-formed testaceous young 

 one. 



This species ranges from low-water mark (though not, 

 strictly speaking, ever a littoral shell) to sixty fathoms, 

 abounding most in about fifteen or twenty. It lives in 

 crevices of stones and shells, and Lamiaaria-voots, or gre- 

 gariously in the mud, filling cavities of dead bivalves, such 

 as Tapes virginea, and sometimes, though les3 frequently, 

 quite free. It is generally distributed around our shores, 

 ranging from Guernsey (S. H.) to Zetland ; so generally, 

 indeed, that though not reckoned one of our commonest 

 species, a few localities only, illustrative of range in depth, 

 may be mentioned : — Portland in fifteen fathoms ; Pen- 

 zance in twenty ; Anglesey in twenty-five ; Isle of Man in 

 twelve to twenty-five (M'Andrew and E. F.) ; Northum- 

 berland, at the roots of seaweeds, &c. (Alder) ; Zetlands, 

 at low water, and in five, ten, twenty, and sixty fathoms 

 (M'Andrew) all round the west coast. In three to ten 

 fathoms in Clew, Clifden, and Killery bays (W. Thompson, 



