NERITACEA. MOLLUSCA. NATICA. 231 



FAMILY NERITJlCEA, LAM. 



Shell semi-globose or depressed-oval, the inner lip like a parlial partition, 

 operculated ; residing in fresh and in salt water. 



GENUS NATICA, BRUG. 



Shell sub-globular, umbilicated ; aperture entire, semi-circular ; 

 inner lip oblique, with a callus which modifies the umbilicus, and 

 sometimes covers it ; operculated. 



NATICA HERDS. 



Shell sub-globose, ash-colored, whorls five, a dark, chestnut- 

 colored band revolving about the three upper ones ; umbilicus large 

 and simple. 



FIGURE. 160. 

 State Coll., No. 57. Soc. Cab., No. 79. 



Natica heros, SAY ; Journ. dead. Nat. Sc., ii. 248. 



Shell globose-ovate, thick, ash-colored, or sometimes brownish, 

 shining when divested of its thin, yellowish epidermis ; distinct 

 lines of growth, and very minute revolving lines cover the surface ; 

 whorls five, very convex, slightly flattened near the top, so as to 

 present a slight angular appearance ; the three posterior whorls 

 have the lower half of a dark chestnut-color, and the other half 

 rather lighter than the rest of the shell ; suture well marked ; 

 aperture ovate ; the lip, sharp above, becomes thicker and smooth- 

 ly rounded, and as it rises by the side of the umbilicus it expands 

 to a considerable breadth ; a very thin layer of enamel is spread 

 over the portion of the whorl which completes the aperture ; 

 throat of a delicate, somewhat clouded chestnut-color, with a 

 margin sometimes bright -yellow ; umbilicus large, rounded, dis- 

 playing the whorls nearly to the summit, coarsely wrinkled, the 

 callus covering only a very small segment of it. Operculum 

 horny. Ordinary length 2| inches, breadth 2 inches. 



It is found on sandy or muddy beaches along the whole coast ; 

 but much more seldom to the south than to the north of Cape 

 Cod. 



