136 



POPULAR CONCHOLOGY. 



the second and third minute, and bounded by numerous 

 uncini, the first of them very large, broadly hooded, and 

 denticulated, the remainder narrow and linear.* — Above 

 100 species; also fossil. 



The shells of Nerita are often beautifully marked and 

 sculptured ; they are brought from the Eastern and Ame- 

 rican seas, a few species only being European. The N. 

 peloronta is called the bleeding tooth, from the red stain 

 about the teeth of the inner lip. Many of the opercula 

 of these shells are very curious; they have a little ap- 

 pendage on one side, which fits into a hollow at the lower 

 end of the inner lip, and against which it turns almost 

 like a door on its hinges, when the animal protrudes itself. 

 Lamarck divided the genus into two — the Neritse, marine 

 shells, and the Neritinae, fluviatile; and Mr. Gray remarks 

 that the opercula differ in the following manner : — those 

 of the Nerita are horny, covered on both sides with a hard 

 shelly coat, which may be separated from the horny part ; 

 whilst the Neritina has a solid, shelly operculum, furnished 

 with a thin flexible outer edge, and slightly toothed on 

 the straight side. 



The fluviatile species are found in the East and West 

 Indies, the Isle of France, &c. ; they are exceedingly 

 pretty shells, frequently ornamented with spots, bands, or 

 zigzag lines, upon a light ground, and are beautiful when 

 examined with a lens : the Indians wear them as orna- 

 ments. The N. corona is coated with a black epidermis, 

 and has a row of long black spines on the whorls ; the 

 N. viridis, a very small green species, is found in the 

 West Indies. N. fluviatilis is found in the rivers of Eng- 

 land adhering to stones ; this shell is often covered with 

 incrustations, and the spire, like many other fresh-water 



* Forbes' s British Moll. 



