( 67 ) 



3. CONCHYUUM. CUV. 



Entirely aquatic or 

 breathing by branchiae. 



a. Ampullaria. 



Animal not yet de- 

 scribed, but probably re- 

 sembling the Paludina. 



b. Melania. 



c. Phasianella. 



Double lips notched 2 Long tentacula. 

 and fringed, each wing 

 with three filaments. 



d> Ianthina. (1) 



A vesicular organ un- 

 der the foot, like a fro- 

 thy ball but solid, which 

 admits of floating but 

 not of creeping; head 

 like a cylindrical trunk, 

 month with little fangs. 

 PI. 14, fig. 13. 



4. Nerita. Lin. 



Shells with the colu- 

 mella straight, the mouth 

 semi-circular or semi-el- 

 liptic, and closed entirely 

 by an operculum. 



Animal not well known. 



Eyes on two tubercles 

 at the outer base of the 

 tentacula. 



Tentacula simple. 



Eyes at the base of the 

 tentacula. 



Eyes on stems at the 

 side of the tentacula. 



a. Natica, Lam. 



Foot large; opercu- 

 lum horny. PI. 17, fig. 

 17,18. 5 



b. Nerita, Lam. (2) 



Foot moderate ; oper- 

 culum stony. PI. 17 

 fig. 11, 12. 



c. Neritina. 



Foot moderate ; oper- 

 culum horny. • • . . 



..sheds a thick .i,„„ r of f deep ^SSSSSJ^^X^ 



.MbTiinT;r«'r f some «**»**. ***** ■**.»«*, » re . rticu . 



