MANUAL 



OF 



Structural and Systematic. 



WITH ILLUSTEATIONS OF THE SPECIES. 



By GEORGE W. TRYON, Jr. 



CONTIXUATION BY 



HENRY A. PILSBRY, 



Conservator of the Conchological Section of the Academy of 

 Natural Sciences of Philadelphia. 



Vol. XVII. 



SCAPHOPODA. 



BY 



H. A. PILSBRY and B. SHARP. 



APLACOPHORA. 



INDEX TO GENERA AND SUBGENERA, VOLUMES II to XVII 



PHILADELPHIA: 

 ^Published by Conchological Section 



ACADEMY OF NATURAL SCIENCES, 



OF PHILADELPHIA. 



1897-8. 



