ON MOLLUSCA OF THE WEST COAST OF NORTH AMERICA. 



625 



* The young shell is thin, semitransparent, with Alaboid tuberous vertex. The nuclear 

 pnif is rather more tumid than the next wliirl, and set slanting as in some Chrysodomi. 

 Adolescent, whirls graooth. except a sutural line. Sculpture of adult gradually developed, 

 W'th spiral lines, sometimes all over, sometimes only anteriorly and posteriorly. Last 

 whirl sometimes with blunt radiating riblets, but generally smooth. Siphonal notch deeplj 

 cut bark, as in Sirmnbina, to which the species may belong. 



18G3. - -i-i I • , - 



