Orr, Robert T.,  1908- <br/><br/>
Vertebrate biology / 
by Robert T. Orr 
 - 2d ed. 
 - Philadelphia :  Saunders ,  1966. 
 - xii, 483 p. :  illus., maps. ;  25 cm. 
<br/><br/>Includes bibliographies. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Vertebrates