EXPLANATIONS OF TERMS. 327 



Tentaeuta, often called feelers ; organs supplying the place of bands and arms to 

 some animals, intended both for feeling, and for seizing and holding food or 

 other substances, or conveying them to the mouth. 



Testaceous, having a shelly covering, but without joints or articulated limbs. 



Thorax, the chest, a cavity in the body formed by the back-bone behind, the ster- 

 num before, the ribs on each side, and the diaphram below, which last sepa- 

 rates it from the abdomen. 



Triturate, to pound up, or reduce to powder, as in a mortar. 



Truncated cone, a cone divided, cr cut off. 



Uiiicalccd, having only one shell or valve, applied to shell-fish, as the cockle, 

 nautilus, &c. 



Vascular, consisting of vessels ; relating to vessels, i. e. arteries, veins, tc. 



Venous, appertaining to the veins. 



Ventricles, muscular cavities of the heart, which receive the blood from the auricles, 

 and transmit it by their contraction through the arteries. Their office is 

 described, pp. 24, 25. 



Vertebra, the bones of which the back-bone is composed. 



Vertebral, having vertebra: ; used to designate one of the grand divisions of the ani- 

 mal kingdom, and including those animals which have an internal skeleton. 



Viscus, pJural Viscera ; used principally to designate organs contained in the great 

 cavities of the body, as the brain, heart, stomach, &c. 



Viviparous, producing young alive. 



