THE NAUTILUS. 51 



tion of the shell is also impaired and the limey portion made more 

 conspicuous through its general bleaching effect and whitening of 

 the callus of the columella. jNIr. Trvon's Physa politisshna, col- 

 lected by Rev. J. Rowell, at Sacramento, and described and figured 

 in Am. Journ. Conch., Vol. I, 1865, is probal)ly one aspect of Lea's 

 P. triticea. It is from a lower station, with an elevation variously 

 stated as from thirty-one to eighty-two feet above sea level, and 

 within the same drainage system. 



The summing up of the foregoing leads to the conclusion that the 

 first-named species (that made by Dr. Lea) is but a dwarfed and 

 arrested aspect of P. gyrina, and Mr. Trvon's species is but another 

 facies of the same. 



Of the number of species that have been made upon characters 

 that are simply those of adolescence, it would be interesting to know. 

 Doubtless a great many, and not only among the fluviatile and 

 lacustrine forms, but among marine forms also. This fact almost 

 daily presents itself where one's routine work is the selection of 

 specimens or examples for a great museum, and the determination 

 of species from a great mass of material. Sometimes one is led to 

 think that it is a pity, either that animals are not born fully grown, 

 or that those who describe them do not bear in mind the fact that 

 mollusks, etc., like men, have to advance by gradual growth from 

 babyhood and the various stages of adolescence to maturity. 



HELIX NEMORALIS IN VIRGINIA. 



BY H. A. PILSBRY. 



The H. nemoralis does not appear to have been naturalized in 

 America except at Burlington, New Jersey, where it was introduced 

 by Mr. W. G. Binney, many years ago. A short time since, I 

 received a parcel of nemoralis shells from Prof Jas. H. ISIorrison, of 

 Lexington, Va. In response to a letter of inquiry Prof. Morrison 

 gives the circumstances of its introduction as follows : 



" The first specimen was found in the grounds of the Virginia 

 Military Institute, in 1886, and was sent to Prof Baird, who called 

 it ' Helix hortensis,' stating that this was a new locality. A few 

 days afterwards I found quite a number of specimens and sent part 

 of them to Mr. Tryon, who said they were ' Helix nemoralis ', and 

 gave all the necessary information to establish this point. I found 



