xxvi Explanation of Terms. 



Tubicolar. Inhabiting a tube. 



Univalve. With one shell or opening. 



Ventral. Belonging to the belly. 



Vertebrated. Having a jointed spine-bone. 



Viscera. The organs contained in the cavities of the body. 



Viviparous. Bringing forth the young alive. 



Webbed. Connected by a membrane, as the toes of aquatic 



birds. 



Xylophagous. Wood-eating. 



Zoologists. Writers on animated nature. 



Zoology. The history of animated nature. 



