The Notch-side Shells 



But it is not drawn out into needle-like extremities as some species 

 are. Its whorls are flat, sculptured by revolving grooves and 

 marked by brown lines that follow the strongest ridges. The 

 ground colour is yellow, with a tinge of red. The notch is a mere 

 sutural curve in the lip. The aperture widens below. Length, 

 2 to 3 inches. 



Habitat. — California. 



The Left-handed Notch-side (P. perversa, Gabb.) coils its 

 ten or twelve rounded whorls so that the aperture is on the left 

 side, contrary to the usual univalve rule. This is a slim little 

 shell with very graceful curves, including a very decided S shape 

 in the lip which forms a deep notch below the suture. Wavy 

 longitudinal striations cross the whorl which are sculptured with 

 fine spiral lines. The colour is reddish brown with an indistinct 

 band of white in the middle of the whorl. Over all, in life, is a 

 greenish gray epidermis. Length, i to 2 inches. 



Habitat. — Southern California. 



The Tipsy Notch-side {P. vinosa, Dall) is a shorter, stouter 

 shell, with rounded whorls and deep sutures. It is sinistral and has 

 a wide notch formed by the S-curved lip. Length, about i inch. 



Habitat. — Aleutian Islands. 



The Girdled Notch-side (P. circinata, Dall) is a well pro- 

 portioned spindle shell, coiled dextrally; each whorl has a cen- 

 tral raised girdle or keel. The lip flares outward to form the notch. 

 Half the length of the shell is occupied by the large aperture. 

 Length, 2 to 3 inches. 



Habitat. — Behring Sea. 



The Unarmed Notch-side {P. inermis, Hds.) represents a 

 section of the genus distinguished by the slender spire, short 

 curved canal, thick lip, and a sinus near (but not reaching) the 

 suture. The pinkish gray exterior is cut by fine revolving ridges 

 and cross grooves with a sharp angle at the middle of each whorl, 

 giving it the appearance of "herring-bone" decoration. The 

 colour shades deeper in the hollows. Length, 1 § inches. 



Habitat. — Southern California. 



The Carved Notch-side (P. incisa. Carp.) is shaped like the 

 preceding species, but smaller, with more convex whorls, and 

 sculptured with fine revolving chestnut lines. It is a fraction 

 over an inch in length. 



Habitat. — Puget Sound. 



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