GLOSSARY 197 



Tib'i a, (i) the shin-bone; (2) the fourth joint of an insect's leg. 

 Tooth, (i) an organ used in mastication; (2) a tooth-lilce projection. 

 Xra'che a, a tube which carries air either to the respiratory organ or to the 



tissues. 

 Trunk, the portion of the body between head and tail. 

 Tu'ber cle, a knob-like projection. 



Ul'na, that bone of the forearm which is on the same side as the little finger. 

 Um'bo (pi. umbones), an elevation near the anterior end of a bivalve shell. 

 TJn'gu lates, hoofed mammals. 



U re'ter, a duct connecting the kidney with the urinary bladder. 

 U'ro style, a long bone forming the hinder extremity of the vertebral column 

 of tailless amphibia. 



Vac'u oles, small, clear spots in cells, filled with a watery fluid. See Food- 



vacuoles and Contracting vacuoles. 

 Valve, (l) a membranous fold which allows the blood, or other fluids, to flow 



in only one direction; (2) one of the two parts of the shell of a bivalve. 

 Vein, (i) a blood-vessel carrying blood toward the heart; (2) one of the 



tubular thickenings of an insect's wing. 

 Ve'na ca'va, a large vein emptying into the right auricle of the heart. 

 Ven'tral, situated on the under surface. 



Ven'tri cle, any cavity of a hollow organ, as of the brain or heart. 

 Ver'mes, the worms, a poorly defined group of animals, showing bilateral 



symmetry but without segmented appendages. 

 Ver'te bra, one of the bones of the spinal column. 

 Ver'te brates, animals having a backbone. 

 Vi bris'ss, long hairs on the face. 

 Vis'ce ra (pi. of viscus) , the organs of one of the great cavities of the body 



(the abdomen, the thorax, or the cranium), usually meaning those of the 



abdomen. 

 Vi va'ri um, a cage in which living animals are kept. 



Warning colors, bright colors which render an animal free from attack. 

 Whorl, a single coil in the spire of a gasteropod shell. 



Yolk, food material of an egg. 



