MANUAL 



OF 



—7^ 7 r 



T 



Structural and Systematic, 



WITH ILLUSTRATIONS OF THE SPECIES. 



By GEORGE W. TRYON, jR. 



COXliEr.VATOR OF THE CONCHOLOGICAL SEC'TIOX OP THK AfATlKMY OF XaTITIAI, 

 SCTENCKS OK PHILAUKLrm,V. 



\'(>1>. ML 



TRlTOiNIDi:, FUSID/E, liUCCmiD.^i. 



PHILADELPHIA: 

 Published, by tlio AiilUoi^, 



Academy of Natural Sciences. Cor 13th & Race Stc. 



1881. ^ '^ ^ -'^5 



