Glossary 683 



Vacuole — a cavity in the cytoplasm of the cell which is filled with fluids. 



Valve — a structure for closing a passageway or opening. 



Vein — a blood vessel which returns blood toward the heart. 



Ventral — away from the back; opposite to dorsal. 



Venuole — a small vein. 



Ventricle — a cavity in an organ. 



Vermis— the median part of the cerebellum. 



Vertebra — one of the individual bones forming the spinal column. 



Villus — a small fingerlike vascular process. 



Viscera^the organs of the coelomic cavity. 



Visceral skeleton — that portion of the vertebrate skeleton derived from the 



primitive gill arches. 

 Viviparous — producing living young. 

 Vitamin — an essential food substance that the body is unable to synthesize. 



Z 



Zoogeography — the study of the geographical distribution of animals. 



