158 



as well as by other less striking characters. The animal has a 

 large fleshy cylinder, containing two tubes, one for respiration and 

 the other evacuation, situated at the posterior extremity. The 

 foot is small and compressed, placed at the opposite extremity or 

 near it. 



It is a littoral genus, inhabiting estuaries and near the mouths 

 of rivers. 



Blainville unites this genus with Ligula, Leach, under the 

 ereneric name Lutrkola. Lamarck describes eleven recent and 

 one fossil species. 



LuTRARiA LINE AT A. — Specific character. Posterior margin 

 with a reflected edge and submarginal carinated line. 



Lutraria lineata, nobis. Jour. Acad. Hat. Sc. vol. 2, p. 310. 



Lutraria papyracea ? Lam. Anim.sans Vertebr. vol. 5, p. 470. 



Ohs. The elevated line of the posterior submargin and the re- 

 flected posterior edge are very characteristic, distinguishing this 

 species from all others, excepting the figure 2 of the plate on 

 Lutraria in the second volume of Mr. Sowerby's excellent work 

 on the " Genera of Recent and Fossil Shells." Our shell is much 

 shorter on the posterior end than his figure, which he refers with 

 doubt to the pa2yyracea of Lamarck; a difi"erence which, however, 

 may be attributable to an inequality of age, as it becomes more 

 elongated anteriorly in the older' shell. Whether or not the present 

 species is the same as that of Lamarck we cannot at present de- 

 termine, but it is without doubt closely allied to it. Still, how- 

 ever, it does not agree with the figure in the Eneycl. Meth. 257, 

 fig. 2, a, b, quoted by Lamarck. PI. 9. 



Paludina. — Shell fluviatile, conical, subovate or suboval, cov- 

 ered by an epidermis ; spire moderate ; whorls convex ; aperture 

 longer than broad, angulated above, simply rounded at base ; la- 

 brum simple, acute, united above to the extremity of the labium ; 

 labium simply arquated ; operculum corneus or coriaceous, subor- 

 bicular, slightly angulated above. 



Ohs. The species of this genus were widely separated from each 

 other by former authors, and referred to the Genera Helix, Turbo, 

 Bulimus, Nerita, and Ci/clostoma ; but Lamarck selected and em- 

 bodied them under the present designation, and they now consti- 

 tute a natural group. 



