1893.] • NATURAL SCIENCES OF PHILADELPHIA. 253 



The geographic distribution is a wide one — all Europe and the 

 Atlantic side of North America. I have seen it from the Pyrenees; 

 France : Lyons, among a lot of pulchella, collected by Locard ; 

 Great Britain (no loc, in Nat. Mus. Coll.) ; Germany : Metz, Dres- 

 den and Neu Haldensleben in Saxony; Austro-Hungary : Brosteni 

 in the Karpathiau Mts. ; Switzerland: Jura Mts. near Brugg; 

 Caucasus. In North America : Washington, D. C.,with pulchella; 

 New Jersey : Princeton, Cape May, etc. ; Pennsylvania: near Phil- 

 adelphia ; New York : Staten Id., Litchfield, Mohawk and other 

 places; Massachusetts: New Bedford, etc.; Maine: Saco, Cape 

 Elizabeth, etc. ; Halifax, N. S. and Quebec in Canada ; Ohio ; New 

 Philadelphia, not found in loco, but in drift on the Tuscarawas 

 River. Further west it has not been noticed, so far. Among 

 numerous lots of V. pulchella from Indiana, Illinois, Michigan, 

 Wisconsin, Iowa, Tennessee and other States, I have not seen one 

 example. 



It is distinguished from the last-named species by its size, aver- 

 aging a little smaller, by the somewhat elongated outline of shell 

 and umbilicus, the last whorl more expanding toward the aperture, 

 the smaller and less elevated spire, the less deep suture, the peristome 

 little and not abruptly everted ; the difference in this is most marked 

 at the periphery (as clearly shown in fig. 9, compared with 2). 

 There are also differences in the jaw and radula, as pointed out in 

 the respective descriptions. One marked characteristic of V. 

 exceutrica is the white lip shining through the shell above and at 

 the periphery, as it does in no other species. 



There is another peculiar feature: quite frequently, especially 

 from certain places, there are very small, whitish dots on the sur- 

 face of the shell, round, or irregularly shaped, single or confluent. 

 They are effected by the loss of the epiconch and evidently indicate 

 a change in the structure of the shell and may be caused by the 

 invasion of a fungus organism. This is the more probable as over 

 many of the spots, especially those less marked and noticeable, the 

 epiconch is apparently intact ; probably they would show only 

 microscopic defects. These abrasions often become so extended as 

 to cover a great part of the surface. 



Our species is variable only within narrow limits. The size varies 

 little above or below the average. Some specimens and local 

 forms show less of that characteristic elongate outline of shell 

 and umbilicus, and yet are not to be mistaken. There is also some 



