224 WEST AMEEICAN SHELLS STEARNS. 



in either of his reports to the British Association, probably for the 

 reason that its habitat was exterior to the geographical limits covered 

 by said reports, or south of the range of coast covered by his investi- 

 gations. His reference to planiusGula was no doubt owing to Dr. Gould's 

 opinion of its identity with Conrad's argentaria. 



If my conclusions, resting upon a careful consideration of the descrip- 

 tions published, as well as a comparison of the figures when given, and 

 further upon diagrams carefully worked out from the measurements as 

 published where figures are lacking, are correct, it is altogether certain 

 that the number of species as alleged must be greatly reduced. With 

 the dominant West American form and its varied aspects I am per- 

 fectly familiar, having seen and handled a large number, as well as col- 

 lected it, and of the identity of the forms described by Conrad and Sow- 

 erby I have no doubt. Thouc^h Conrad's argentaria is the most familiar 

 name and in general use, and again more appropriate than Sowerby's 

 planimcula, yet, as a matter of fact, the latter's has priority by three 

 years. It is highly probable, hardly a doubt, that Hanley's obtusa, C. 

 B. Adams' alta, Carpenter's excurva, and Sowerby's lentimlaris all fall 

 to the rear as synonyms. Conrad's Leana, included by Carpenter in the 

 Smithsonian checklist of the shells of the west coast of North America, 

 must be eliminated, as it is an East North American form described by 

 the author* from a Rhode Island specimen. A revised list of the West 

 American spe(;ies will read thus. 



1. Periploma planiusmla Sby. 



+ P. lenticularis Sby. 



= P. argentaria Conr. 



= P. alta C. B. Adams. 



= P. excurva + P. excurvata Cpr. 



2, ? Periploma pap\jraceaC\n. 

 3 Periploma discus Stearns. 



Of the above, 1 and 3 occur in what Carpenter has termed the " Ore- 

 gonian and Californian Province," and 1 and 2 in his " Mexican and 

 Panamic Province." They are however rather southern than northern 

 shells, and I am not aware of their occurrence north of Point Concep- 

 tion. 



*Jour Acad. Nat Sciences, Pliila., vi. 263, PI. 11, Fig. 11. 



