BULBUS, • 347 



Genus BULBUS, Brown. 1839. 



Shell ventricose, imperforate ; spire with the apex acute ; whorls 

 smooth, Avithout epidermis ; aperture very wide ; inner lip with a 

 large, smooth callus covering part of the body whorl and concealing 

 the umbilicus. 



Bulbus flavus. 



Fig. 162. 



Shell thin, sub-globose ; aperture large ; inner margin sinuous ; umbihcus none. 



Natica Jfara, Gould, Sillim. Journ. xxxviii. 196 ; Inv. 1st ed. 239, fig. 162. — De Kay, 



N. Y. Moll. 123. 

 Bulbus flavus, Stimpson, Check Lists, 5. 



Shell of an inflated, globular form, light and thin, white, with a 

 bright straw colored or golden epidermis ; surface very minutely 

 checkered witli very faint, revolving lines, and 

 lines of growth ; spire very little elevated, com- ^'^ ^^^• 



posed of four rounded whorls, a little compressed 

 behind, near the suture, which is faintly im- 

 pressed ; aperture occupying one half the infe- 

 rior aspect of tlie shell, broad oval, modified by a 

 curve which looks as though it might be caused 

 by a contraction and obliteration of the 'umbili- 

 cus ; outer margin very sharp ; umbilical region ^ fla«i«" 

 about the middle of the left margin much retreat- 

 ing, and deeply indented in most specimens, though evidently 

 never open ; a thin callus, commencing at the upper angle, expands 

 and thickens over this region, then, narrowing, forms a tliick, 

 rounded, ivory, vertical margin to the front of the shell. Length, 

 about one inch; breadth, a little less. 



From the collection of Colonel Totten, who obtained it from the 

 Bank fishing grounds. Rimouski {Bell) ; Halifax, Banks ( Willis) ; 

 Eastport (^Cooper). 



. The aspect of this shell immediately suggests the Helix aperta, 

 Born {H. naticoides, Drap.), to which it bears a very striking re- 

 semblance in shape. If the existence of an umbilicus is an essen- 

 tial characteristic of the genus Natica, and so it is laid down by 

 Lamarck, this shell cannot come under it. There is no approach 

 to an umbilicus, even in the youngest specimens, the space intended 



