222 GLOSSARY. 



Vestigial. An organ that remains undeveloped and has no function; 

 rudimentary as applied in anatomy. 



Viscera. Internal organs taken collectively. 



Visceral mass. Applied to the portion of a mollusk that contains stom- 

 ach, intestine, liver, gonads, etc. 



Vitellarium. A female reproductive gland that supplies cells to be used 

 as food for developing embryos. See Bdelloura. 



Vitelline glands. Same as vitellarium. 



Water tube. One of the tubes between the lamellae of a lamellibranch 



gill. 

 Whorl. A turn of the shell of a gastropod. 



Yolk-mass. A mass of food material for the nourishment of an embryo. 



Zoophyte. An animal that is somewhat plant-like in appearance. 

 Zoo id. One of the individuals in a united colony of animals. See Obelia 

 and Bugula. 



