128 UNIVALVES NERITA, 



NERITA.— Nerite or Moof-Shell. 



Animal — a Limax: Shell univalve, spiral, gihhons, flfft- 

 tish at bottom; aperture semiorhicular or semilunar ; 

 pillar-lip transversely t7'uncate, Jlattish. 



There are a few out of the seventy -six species which 

 compose this genus that have some claim to beauty, 

 though uone can boast of great rarity or value. 



There is considerable variation in the form and markings 

 of the Neritae : some are spiral, with prominent whorls ; 

 others have their wliorls partly or wholly concealed; 

 some are greatly umbilicate or perforate; others are per- 

 fectly entire and solid ; and maiiy have the umbilicus 

 partirlly covered by a repand lip, or fissurated nodule. 

 The interior of the month and lips is, in many species, 

 toothless; whereas, in others, both lips are beset with 

 strong, prominent, and articulate teeth, often terminat- 

 ing in disjointed, elevated strips or protuberant granula- 

 tions. 



In most species the back of the shell is covered with 

 strong, elevated ribs, sometimes nodulous and imbricate; 

 in others the shell is only minutely striate; and in many 

 the surface is so perfectly smooth as to afford a brilliant 

 polisli. 



Among those species which are umbilicate the follow- 

 ing may be quoted: viz. Nerita canrena or tabby-cat 

 Nerite, (of which there are many beautiful varieties), Ne- 

 rita canccllata, Nerita glaucina, Nerita vitellus, and Ne- 

 rita mannnilla, commonly known by the name of the 



