98 TRACHELIPODA. 



Genus 56.— NERITA.— /-amarc/^. 



Generic Character. — Shell solid, semiglobose, flattened 

 below, without an umbilicus ; aperture semi-orbicular and 

 entire ; inner lip depressed, septiform, thin-edged, and fre- 

 quently dentated or crenated; outer lip obtuse, and often 

 provided internally with teeth. 



Nerlta peloronta. — The Blood y-tooth Nerita. Plate 



XII. fig. 13. Thick, transversely sulcated; gray or red- 

 dish-yellow, with variously coloured bands ; inner lip with 

 two teeth or crenulations, having a bloody mark at their 

 base. One inch long. Inhabits the seas of South America 

 and the West Indies. 



Genus 57 NERITOIDES.— ^/om^w. 



Generic Character. — Shell strong, thick, subrotund; spire 

 depressed; aperture nearly round; lip almost continuous, 

 having a slight groove only at its junction with the body; 

 no umbilicus. 



Neritoides Utoralis. — The Score Neritoides. Plate 



XIII. fig. 24. Smooth, covered with an olive-green, yel- 

 low, brown, or otherwise coloured epidermis, sometimes 

 beautifully banded or chequered beneath it; inside generally 

 purplish-brown ; body very large ; spire very short and de- 

 pressed. Five-eighths of an inch long. Inhabits the shores 

 of Northern Europe. 



This shell is the Turbo neritoides, and Turbo retusus of Lamarck. 



Genus 58.— NERITIN A.— XawmrcA. 



Generic Character Shell rather thin, semiglobose, or 



ovate, flattened below ; without an umbilicus ; aperture 

 semicircular ; inner lip flattened, and reflected on the colu- 

 mella, sometimes slightly crenated ; outer lip destitute of 

 teeth or crenulations on its internal face; aperture provided 

 with an operculum, having a lateral point. 



Neritina fiuviatilis. — The Fresh-water Neritina, 



