TRAOHELIPUUA. 



99 



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

 white, 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. 



Genus 59.— 'SAYlCELh A.— Lamarch. 



Generic Character. — Shell elliptical or oblong, convex 

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

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

 provided with a solid flat operculum, having a lateral acute 

 point. 



Navicella elUptica. — 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 France, India, 

 and the Moluccas. 



FAMILY Vir. PERIrfTO.MIDA. 



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

 ture united; aperture protected by an operculum; fluviatile, 

 and the animal respiring water. 



GewMS 60— AMPULL ARIA.— Zamarc/e. 



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, 



Ampullaria Giiyanensis. — The Guiana Ampullaria. 

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

 tudinal stricc ; covered with a fuscous-brown epidermis ; 

 inside golden-yellow. Three inches in diameter. Inhabits 

 the rivers of Guiana. 



Genus CI.— PALUDIN A.— Zawarc/i. 



Generic Character Shell conoid; volutions rounded or^ 



i2 



