The Sea Snails. Bleeding Tooth 



gravelly bottoms of clear rivers ; it extends over a very large area, 

 and has many varieties, some of which live in brackish water, 

 and a few in salt water. The shell is transverse, the last whorl 

 much swollen, white or decorated in a great variety of colours 

 and designs. The largest are about J inch in diameter. 



This mollusk lays its globular egg capsules on the shell of 

 another individual. Each capsule contains fifty or sixty eggs. 

 But only one of these develops. The remaining eggs serve to 

 nourish the one growing offspring the capsule contains. We are 

 strongly reminded of the "Yarn of the Nancy Bell." It would 

 seem an unnecessary expense to feed a favoured individual on 

 his own brothers and sisters because he happened to be the first 

 to hatch, and so had them at a disadvantage. 



N. reclivata, Say, is an olive or light brown shell, marked 

 with fine zigzag Hues of black, and about f inch in diameter. 

 It is found in inland rivers of Florida. N. viridis, Linn., is a 

 small bright green marine species. It is rarely found on Florida 

 and Texas coasts. 



N, Virginea, Linn., West Indies to Brazil, has a beautifully 

 polished shell with markings of white and Quaker drab and gray 

 which are strikingly like the plumage of a Guinea fowl. 



Some Neritinas resemble the slipper shells in form. Some 

 add to the boat shape two wide lateral wings, doubling the width 

 of the boat's seat. The animal is often as highly coloured as its 

 shell, with broad foot, an enfolding mantle lining the shell's 

 mouth, and long, slender tentacles. 



Genus NAVICELLA, Lam. 



Shell oblong, limpet-like, apex on posterior margin, columellar 

 shelf broad, not toothed, operculum shelly; nucleus lateral. 



This genus of about fifty species is briefly mentioned here 

 because its shells in a collection are likely to be referred to the 

 limpets or the slipper shells, both of which they resemble. They 

 come from the East Indies and Polynesia, where they live on 

 floating sticks and roots of palm trees so as to be near the water. 



N. Janelli, Reel., looks like half of a bivalve shell, round- 

 ish like a scallop, the beak at one end, Narrow longitudinal 

 ridges are crossed by occasional lines of growth. 



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