248 BUM PUS. [VOL. I. 



by Willis. He evidently had no idea that the Massachusetts 

 shore was soon to be invaded. In the same year Mr. Charles 

 B. Fuller, curator of the Portland Society of Natural History, 

 found a few specimens in Maine at Portland and at Kennebunk 

 (Morse, '80). 



In 1871 the species was found at Hampton Beach, New 

 Hampshire (Gray, '79). 



In 1872 Professor Morse found it at Salem (a single speci- 

 men), and Verrill ('80) found it " very rare " at Provincetown, 

 Mass. 



In 1875 two specimens were taken at Woods Holl, Mass. 

 (Verrill, '80). 



In 1880 Prof. S. I. Smith found the first specimen at New 

 Haven. 



At all of these localities the shell became abundant in a very 

 few years after its first appearance. 



Thus the history of the introduction, the rapid dispersion and 

 the remarkable increase of the periwinkle are not essentially 

 different from that of the introduction, dispersion, and increase 

 of the sparrow. 



It is, of course, well known that Littorina littorca is, on its 

 native shore, like many gasteropods, subject to variation (Jef- 



FIG. i. Coast line of New England, indicating the localities from which collections of 

 Littorina littorea have been made. I, St. Croix River; II, Casco Bay; III, 

 Beverly; IV, Nahant; V, Plymouth; VI, Seaconnet ; VII, Newport ; VIII, Bristol ; 

 IX, Bristol ; X, Warren River. 



freys, '65). Jeffreys gives the diagnostic characters of four 

 " varieties," though these are not characterized by definite 



