TROCHUS. 503 



nearly so, rather abruptly shelving - , well defined at the 

 suture, and moderately broad, that is to say their length 

 is equal to about one-third to two-fifths of their breadth. 

 They are spirally girt with a rather broad and prominent 

 basal belt, and with about five or six obliquely subgenicu- 

 lately granular raised stria?, whose interstices — which, in 

 the final volutions are much broader than the stria? — 

 are erowdedly traversed by very oblique raised wrinkles, 

 that, in certain specimens, are so immediately connected 

 with the granules, as to form continuous series of produced 

 tear-drops. The prominent belts, likewise, are not simple, 

 but granular and spirally striated : the elevated lines upon 

 the base are decidedly broader, rather more distant, and 

 as well as their interstices, faintly exhibit the superior 

 sculpture. The aperture is subquadrate, but very much 

 broader than long, the width being fully equal to half the 

 basal diameter, whilst the height does not occupy one- 

 third of the total length of the shell. It is not adorned 

 with any other sculpture than the indications of that of 

 the exterior upon its silvery nacre ; the outer lip is acute, 

 and subrectangular below ; the pillar is white, very short, 

 nearly rectilinear, and slightly oblique. One of our larger 

 specimens is nearly seven lines in length, with a base of 

 fully half an inch in diameter. The coloured individuals 

 have generally their sculpture more granular and better 

 defined ; in certain shells, too, there are similar, but much 

 finer, spiral striae between the five principal series. 



Although but recently described as a living shell, some 

 Irish examples were in the cabinet of Donovan ; and the 

 individuals engraved by Wood — whose name, though 

 prior, we cannot prefer, owing to the imperfect definition 

 of the species by his reduced figure — came from the same 

 localitv. 



