75 



The Beccjrii perverfus is without doubt perfe6lly diflin<5l 

 from the other, and not a lufiis, or accidental heteroftrophon 

 variety ; it is more numerous than Beccar'ii, and both too 

 common to favour an opinion that one is a lufus variety of 

 the other. 



Nautihis Ijevigatulus, Lin. Trans, vili, p. 1 15. L^vigatulus. 



p. 188. 

 We found this fliell in the Boyfian cabinet, mixed with Tab. 18. f. 7. 8. 

 J^aiitilns (leprejfulus and calcar by miftake ; and a very good 

 drawing of our JV. calcar, from the fame fource, was marked 

 67, refering to that number in Tejlacea Minuta Rariora, 

 which is JV. Icevigatulus; fo that it may be conjedlured thefe 

 two fhells have been generally confounded. Our former 

 defcription of this fpecies was only copied from Walker, as 

 at that time it had never come under our obfervation ; and 

 as we confider tliat author's concife account by no means 

 fufficient to define the diftinguifhing charadlers, we (hall de- 

 fcribe it from the fpecimens before us. 



Shell opaque, fmooth, pale ferruginous-brown, with 

 about ten vifible flexuous rays marking the fepta ; 

 thefe are ratlier deeper in colour, a trifle raifed or 

 embofled, radiating from the centre : both fides are con- 

 fiderably and equally convex, declining to a rounded mar- 

 ginal edge, but not flridlly carinated ; mouth, or exterior 

 feptum furrounded by a margin or rim, forming a triangle ; 

 fo that the body is not interfedied by the anterior end, but 

 the volution is lofl: jufl. below the margin of the firfi feptum. 



K 2. In 



