NIAGARA FALLS AND VICINITY 2/5 



umbilicus — external opening of the hollow axis of a loose coiled shell 

 umbo — area about and including the beak in pelecypods and brachiopods 

 unconformity — irregularity in the succession of rock beds indicating an in- 

 tervening period of erosion 



valvular — pertaining to a valve 



varix — row of spines, a ridge or other mark, denoting the former position of 

 the lip on the shell of a gastropod (plural varices) 



vaulted — arched 



ventral — pertaining to the lower side, or venter 



ventricose — strongly swollen, or bulging 



vesicular — bearing vesicles, or hollow cavities 



vestibular area — area surrounding the cell apertures of some bryozoa; often- 

 depressed 



viscera — the internal organs of the body 



whorl — single volution of a coiled shell 



wing — posterior larger expansion along the hinge-line of a pelecypod 



zoarium — aggregates of the polypites of a bryozoan colony 



zooecium — the bryozoan cell 



zooid— one of the " persons " or individuals of a zoarium 



