578 THE AMERICAN NATURALIST [Vol.XLIV 



Bumpus J s data afterwards by the most approved tech- 

 nical methods, confirmed his conclusion. 



The oyster-borer, Urosalpinx cinereus Say, offers an 

 additional opportunity to test the relative variability of a 

 species when introduced into a new environment as com- 

 pared with the same species living in the original habitat. 

 This mollusk is a native of the Atlantic coast, living par- 

 ticularly on the oyster beds, where it causes considerable 

 damage. In 1871 Mr. A. Booth, of Chicago, first trans- 

 planted the Atlantic oysters to the Pacific coast where, 

 with varying success, they have since been niniiilnincil. 

 Two lots of these shells were obtained from the San 

 Francisco beds in 1898 and it was the original purpose 

 of this paper to compare these introduced California 

 shells with individuals from the Atlantic coast whence 

 they were emigrated. 



The work was principally done at the Woods Hole re- 

 search laboratory of the U. S. Fisheries Bureau and I 

 wish hereby to acknowledge the many courtesies received 

 from the officers connected with that bureau, and particu- 

 larly to express my indebtedness to Professor Bumpus 

 who suggested the original problem. I wish also here 

 to thank the following persons for aid in obtaining speci- 

 mens : Dr. Bumpus for 1,500 California shells ; Dr. H. M. 

 Smith for 1,700 from Prince's Bay, Staten Island; Mr. 

 G. W. Hunter, for 1,000 from Norwalk Harbor, Ct.; 

 Miss M. E. Smallwood for 1,000 from Cold Spring Har- 

 bor, Long Island ; Mr. C. T. Brues and Mr. A. L. Melan- 

 der for 8,000 from Woods Hole, Mass., in 1902 and 1903; 

 and Mr. C. S. Bennett for 4,000 from Woods Hole in 

 1908. Finally, I am particularly under obligation to Dr. 

 J. Arthur Harris, who very kindly passed the manu- 

 script under his statistical eye. It should be added that 

 while Dr. Harris is responsible for much that does not 

 appear he is in no way committed to what remains. 



2. Methods. — In collecting, only living specimens were 

 taken, thus eliminating beach-worn shells, and collecting 

 was always done " systematically at random" (Daven- 



