TRACHELIPODA. 99 



Plate XII. fig. 14. Shell small, oval; back convex, smooth, 

 ^yhite, variously speckled with red, black, or dark brown ; 

 spire inclined, lateral ; lip slightly denticulate. One-third 

 of an inch long. Inhabits the rivers and streams of Europe. 



Genus59.—^AYICELL A.— Lamarck. 



Generic Character. — Shell elliptical or oblong, convex 

 above, concave beneath; spire lowered to the margin; iiuier 

 lip flattened, acute, narrow, and destitute of teeth ; aperture 

 provided with a solid flat operculum, having a lateral acute 

 point. 



Navicella elllptlca. — The Oval Navicella. Plate 

 XIII. fig. I. Smooth, shining, spotted and streaked with 

 purple, blue, or brown ; covered with an olivaceous epider- 

 mis; spire curved, prominent, extending beyond the margin. 

 One inch long. Inhabits rivers in the Isle of Fi-ance, India, 

 and the Moluccas. 



FAMILY VII. rERISTOMIDA. 



Shell conoid or subdiscoid, with the margins of the aper- 

 ture united; aperture protected by an operculum; fluviatile, 

 and the animal respiring water. 



Genus 60— AMPULLARIA.— Za/narcA. 



Generic Character Shell globular, ventricose, umbili- 



cated; inner lip without a callosity; aperture oblong, entire ; 

 margins united ; outer lip acute, but not reflected ; an oper- 

 culum, 



Ampullar ia Guyanensis. — The Guiana Ampullaria. 

 Plate XII. fig. 2. Globular, thick, with unequal longi- 

 tudinal striae ; covered with a fuscous-brown epidermis ; 

 inside golden-yellow. Three inches in diameter. Inhabits 

 the rivers of Guiana. 



Genus 61.— PALUDIN A.— ZawiarcA. 



Generic Character Shell conoid ; volutions rounded or 



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