[ 32 3 
FIG XLL 
The outward volution for half its breadth 
next the back is tranfverfely ribbed, their ends 
bending towards the mouth of the fliell: the 
inner volutions, and the outward one for half its 
breadth next them, are fmooth: diameter near 
two inches: fliell thin of a brown color, 
* With a plain Jurrow m channel along the hacL 
F I G. XLir. 
Volutions tranfverfely ribbed: thofe of iht 
outward volution alternately Ample; the interme¬ 
diate ones for half their length Ample, then bifld. 
Found at Midford. 
* Whofe lacks are ribbed. 
FIG. XLIIL 
Volutions tranfverfely ribbed : thofe of the 
outward volution at Arft Ample, then biAd; 
pafs the back and unite again before they reach 
the inner volution. 
This 
