$1,00 per Year, < $1,12 to Foreign Countries ,) lOcts.acopy, 



THE 



NAUTILUS.** 



A MONTHLY 



DEVOTED TO THE INTEKESTS 

 OF CONCHOLOGISTS. 



EDITOR 



H. A. Pi LSBRY,ConservatorConchologlcal Section, Academy of Natural Sciences 



Philadelphia. 



ASSOCIATE EDITOR: 

 ('. W. JOHNSON, Curator of the Wagner Free Institute of Science. 



Vol. XII. ARRIL, 1899. No. 12. 



CONTENTS: 



PAGE. 

 ON A COLLECTION OF PENNSYLVANIAN MOLLUSKS. By S. N. 



Rhoads .......... . ............ , ....... ; ........ 133 



A NEW PTERONOTUS FROM CALIFORNIA. By Wm. H. Dall. - 138 



How UNIONES EMIGRATE. By Lorraine 8 Frierson . 139 

 DESCRIPTIONS OF NEW AMERICAN LAND SHELLS. By H. A. 



Pilsbry ........... ................................ 140 



ISAAC LEA DEPARTMENT .................... . 142 



GENERAL NOTES ................................. 



Published by 



H. A. PILSBRY, Editor, Academy of Nat. Sciences, Philadelphia. 

 C. W. JOHXSOX, Manager, Wagner Free Institute of Science, Philadelphia. 



Entered at Philadelphia Post-OJtict as second-class matter. 



