98 TRACHELIPODA. 



Genus 56.— NERITA.— XamarcA'. 



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. 



Nerita peloronta. — The Bloody-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 51 NERITOIDES.— ^/^o^tvi. 



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 litoralis. — The S-hore 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 ; spirt very short and de- 

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

 of Northern Europe. 



This shell is the Tiu-bo neritoides, and Tui'bo retusus of Lamarck. 



Genus 58.— NERITINA.— Zama;c/c. 



Generic Character Shell rather thin, semiglobose, or 



ovate, flattened below ; without an umbiUcus ; 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 Jiuviatilis. — The Fresh-avater Neritina. 



