Orr, Robert T.,  1908- <br/><br/>
Vertebrate biology / 
Robert T. Orr 
 - 4th ed 
 - Philadelphia :  W. B. Saunders,  1976. 
 - 472p :  ill ;  27cm. 
<br/><br/>Includes bibliographies 
<br/><br/><label>ISBN: </label>0721670180 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Vertebrates