202 



NATICA. 



NLIUTA CANRENA.- 



-Linn. 



Sowerhys Genera, No 15. pi. 5. 



The species and varieties of this very numerous fa* 

 mily were classed together by Linnaeus under the 

 name of Nerita canrena. Bruguiere first separated 

 them, and adopted Adanson's name to distinguish them 

 from the Neritae, to which they have but a very slight 

 affinity. The shells of this genus are solid, subglobu- 

 lar, umbilicated; aperture entire, semicircular; right 

 lip smooth and sharp; left margin oblique, callous, but 

 not toothed, the callosity modifying the umbilicus, and 

 sometimes closing it entirely; the exterior smooth; oper- 

 culum generally calcareous, ivith concentric ribs, fitting 

 into a slight groove on the columella, though in some 

 species it is horny and smooth: which circumstances 

 arc not observed by Lamarck in his description of these 

 shells. Sowerby mentions the existence of numerous 

 fossil species. 



Natica glaucina 



albumen 



mamillaris 



inamilla 



Natica melauostoma 



aurantia 



conica 



plumbea 



