LACUNA. G5 



Is much arcuated above, but somewhat straightened at the 

 anterior base, where It manifestly recedes. The white 

 pIllar-Hp, which terminates near the junction of the outer 

 one in a moderate-sized but distinct umbilicus, Is pro- 

 foundly canallculated, and overhung by the body-whorl ; 

 It varies in breadth, but in general Is moderately broad, 

 and Its free edge, which is generally sunken, Is slightly 

 concave, and leans a little away from the outer lip. Our 

 larger specimens measure five lines in length, and three 

 and a half In breadth. 



What sve regard as the canalis has an ovate-acute 

 figure, and a rather short spire whose whorls are simply 

 rounded. The body Is a little flattened in the middle, 

 and at times Is distinctly angulated at the beginning of 

 the basal declination, which produces a corresponding 

 eff'ect upon the ajjerture. The breadth of the penult turn 

 Is twice Its length. The mouth, which shares in the 

 general abbreviation. Is nevertheless very large, and occu- 

 pies more than one half of the total length. The pillar- 

 canal is very wide. The dwarf variety quadrifasciata 

 bears much resemblance to this form, but Is solid and still 

 more stunted ; the basal angulation is rendered peculiarly 

 distinct from the surface of the body being decidedly 

 flattened In the middle. The pillar is broad in proportion 

 to the width of the canal. 



Through the kindness of Mr. Alder we are enabled 

 to figure the Cullercoats specimen {^\. Ixxxvi. f. 7) from 

 which he described his L. lab'wsa (Moll. Northumber- 

 land and Durham, p. 58). From the profound respect 

 we entertain for the opinion of that excellent naturalist, 

 we have refrained from citing his species as a synonym 

 of vincta, to which nevertheless two North British spe- 

 cimens in our own cabinet approximate It so closely, 



VOL. III. K 



