$1.00 per Year. ($1.12 to Foreign Countries.) lOcts. a copy. 



THE 



NAUTILU 



A MONTHLY 



DEVOTED TO THE INTERESTS ' 

 OF CONCHOLOGISTS. 



- '' -^'' 



EDITOR: 

 H. A. PILSBR\, Conservator Conchological Section, Academy of Natural Sciences, Philarlelphia. 



ASSOCIATE EDITOR : 

 C. W. JOHNSON. Curator of the Wagner Free Institute of Science. 



Vol. X. 



APRIL, 1897. 



No. 12 



CONTENTS : 



PAGE. 



THE IANTHINAS. By Charles T. Simpson. 133 



VERTIGO COLORADENSIS AND ITS ALLIES. By T. D. A. Cockerel]. . . 134 

 CONTRIBUTION TO A KNOWLEDGE OF UNITED STATES UNIONID^E. By S. 



Hart Wright. 136 



PLANORBIS NAUTILEUS L. IN AMERICA. By Geo. W. Taylor. . . . 139 



ISAAC LEA DEPARTMENT 140 



FOSSILS OF DEAD MAN'S ISLAND. By Hon. Delos Arnold. . . 140 



NOTES ON VITREA CELLARIA MULL. By Mr. Leon Walker. . . . 142 



NOTES AND NEWS . . 142 



PUBLICATIONS RECEIVED. .... .... 143 



Published by 



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



C. W. JOHNSON, Manager, Wagner Free Institute of Science, Philad'a. 



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



