MANUAL 



OF 



ONCHOLOGY; 



STRUCTURAL AND SYSTEMATIC. 



WITTl ILLUSTRATIONS OF THE SPECIES. 



BY GEORGE W. TRYON, JR. 



CONTINUATION BY 



HENRY A. PILSBRY, 



CONSERVATOR OF THE CONCHOLOGICAL SECTION OF THE ACADEMY OF 

 N<.TUHAL SCIENCES OF PHILADELPHIA. 



Vol. XI V\ 



POLYPLACOPHORA, 

 (Chitons.} 



LEPIDOPLEURID^, ISCHNOCHITONID^, CHITONID^, MOPALIID^. 



PHILADELPHIA : 

 Published by Concliolop-ical Section, 



ACADEMY OF NATURAL SCIENCES, 



OF PHILADELPHIA. 



1892. 



