86 THK NAUTILUS. 



theiu teeth, the thinuer shells being as clear of teeth us a typical 

 Mesodon, and only the old thickened shells have the obsolete teeth. 

 They attain a size somewhat larger than the largest specimens of 

 infiecta in the Binney collection. 



Prof. Call believes them to be Triodopsis appressa vi'inor, but they 

 seem to me to be nearer infiecta than appressa, and if not a distinct 

 species, they certainly are a well-marked variety. 



NOTES ON THE VARIATION OF CERTAIN MOLLUSCA 

 INTRODUCED FROM EUROPE. 



BY T. D. A. COCKERELL. 



As I have urged wiien writing of Helix nemoralls, few subjects can 

 be more interesting to the conchologist than the effect of environment 

 on species, which is seen so frecpiently in the case of variable sjiecies 

 introduced into new countries. 



Through the kindness of Mr. W. G. Binney and Prof. J. H. 

 ISIori-ison, I have been enabled to examine specimens of several 

 species of European Mollusca introduced into this country, and to 

 refer them to various varieties already known in Europe, but mostly 

 so far not recognized in the American fauna. 

 (1.) Agriolimax agrestis (L.) var. Sylvaticus. (Moq., non Drup.) 



This is the mottled form of the sj^ecies, and appears to be the 

 prevalent form at Burlington, New Jersey, whence ]Mr. Binney has 

 sent me several living examples. One of these is unusually large, 

 being 53 mill. long. 

 (2.1 A. agrestis var. typica. (Less, k Poll.) 



This is the spotless type, of which I found a single exami^le at 

 St. Thomas, Ontario, Canada, in 1887. 

 (3,) A. agrestis var. reticulatus (Moq.) 



Resembles var. sylvaticus, but is reddish-ochre with black irregular 

 spots, often tending to reticulation on the body. Sent from Burling- 

 ton, N. J. (Mr. Binney). 



(4.) Limax (Lehmannia) variegatus Drp. var. flavis Moq. (=L. flavus " L., " 

 Auctt.) 



Lexington, Va., one example from Prof. Morrison. 



