SOUTHERN SHELLS. 



23 



The shell is plainly marked by three reflexed frills 

 on each whorl, alternating with 

 rounded knobs. In perfect speci- 

 mens there are numerous fine spiral 

 lines of sculpture, which are often 

 indistinct or covered by foreign sub- 

 stances. The aperture is small and 

 oval ; but the most noticeable feat- 

 ure is the canal, which is complete- 

 ly closed, forming a tube, slightly 

 reflexed near its extremity. The 

 length of the shell is nearly two 

 inches; its color is white, though the 

 outside is very dingy, and is some- 

 times striped with brown. 

 Ocinebra Poiilsoni^ Cpr., O-sin-e'-bra Poul'-son-i, 

 has a strong, spindle-shaped shell, and is found about 

 San Diego. Its surface is strongly marked with 

 rounded varices, which are crossed by fine, dark, 

 spiral lines. The walls of the aperture, in mature 

 specimens, are pure white, and within the outer lip 

 are five or six little round knobs or teeth. Let some 

 one try to find out whether these teeth are merely for 

 ornament, or whether they have some useful office. 



The canal is open and somewhat curved, and the 

 operculum is a thin, brown scale. The length of the 

 shell is from an inch to two inches. 



The other Ocinebras are much smaller 

 than the last species, and some of them are 

 rather difficult to determine. Fig. 4 repre- 

 sents the shell of Ocinebra hirida, Midd., 

 lu'-ri-da. This pretty little shell is com- 

 mon at Monterey and other parts of the 

 Fig. 4. coast It is spindle-shaped, and is marked 



