120 



more regular and more approximating: the cicatrix h 

 rather lon'^er, as it exceeds half the breadth of the fhell ; 

 and is joined, or very nearly runs into the marginal bor- 

 der (mentioned in the defcription ot the other fpeciesj for 

 half its lenirih from its bafe. 



o 



It is a much more elegant fhell, efpecially when young, 

 variegated with cinereous, brown, or purple zigzag lines, 

 and fometimes radiated with the fame from the hinge to 

 the oppolite margin; the ground colour of the older (hells 

 is ufually brown, the younger ones white, fometimes with 

 only a few markings at the anterior end. The utmoft 

 fize is an inch and three-eighths in length ; and two inches 

 in breadth : it is mofl commonly broader in proportion 

 to its length than the V. decu/fila, but v\e do not perceive 

 the material diflinflion upon a general review, in the 

 teeth, that Mr. Wood frems to exprefs l)etween thefe 

 two fiiells; and muft confefs the gradations in this refpe6l 

 run fo much into each other that no leading character can 

 be drawn from them. 



This gentleman however is the firft Engli/// author who 

 has properly divided thefe fhells; to whofe definiii(m may 

 be added, that the great leading character befides the 

 ftru6^ure, and fituation of the cicatrix, is the formation 

 of the animal inhabitant: that of the V. decvjfata (as be- 

 fore dated 1 is poflt (Ted of two feparate tubes, whereas the 

 tubes of this are not quite fo long, and connected almoll 

 their whole length, except at the tip. 



This 



