31 



markable for its globular form and lor the numerous obsol 

 lines which seem like equidistant deciduous corrugations of the 

 epidermis, having no effect whatever in modifying the calcare- 

 ous surface, upon which it exhibits no trace. 



P. elongata, Swainson. Capt. Leconte presented me with a 

 shell which, he informed me, he found in the river St. John, 

 Florida, i described it nearly four years since under the name 

 of multilin ata; but, recently, hcing about to publish it, on a 

 more attentive examination and comparison with a specimen 

 of the elongala from Calcutta, given to me by Mr. Hyde of 

 Philadelphia, I have concluded that it varies from that speci- 

 men, only in having the umbilicus a little smaller. 



P. subpurpurea. Shell oblong, subovate. olivaceous, with a 

 tinge of purple more or less intense, sometimes hardly percep- 

 tible: spire rather obtuse, terminating convcxly: whirls five, 

 'Jed, equally convex: suture impressed, but not very pro- 

 foundly: apertun much widest in the middle; narrower above: 

 within glaucous, somewhat perlaceous: labrum rectilinear from 

 the middle upwards: umbilicus none. 



Length, about one inch; greatest breadth, four-fifths of an 

 inch. 



An inhabitant of Fox River, an arm of the Wabash. It is 

 very distinct from any other species 1 have seen. The labrum 

 exhibits no curvature from the middle almost to its junction 

 with the penultimate volution. 



A MPLURI A, Lam. 



A. rotundata. Shell remarkably globose; length and breadth 

 equal, dark brown, but becoming olivaceous towards the aper- 

 ture: spire but little elevated: suture moderately impressed: 

 body whirl a little undulated instead of being wrinkled; these 

 undulations being very perceptible to the finger within the 

 ehcll: ap Hun within on the margin thickened equally all 

 round and fulvous, with a slight groove for the reception of 

 the operculum, hardly visible but palpable: within somewhat 

 perlaceous; a little darker on the columella: umbilicus small, 

 narrow: op rculum calcareous, deeply and concentrically ru- 

 gose, so as to appear stratified: nucleus on the side towards 

 the labium, sub-marginal. 



Length, less than one inch and four-fifths; greatesl breadth, 



about the same. 



