of North American Helicidce, 421 



Helix alternata Say. 



The geographical distribution of" the varieties of II. alternata 

 is interesting. The species attains its largest size in Ohio and 

 Michigan — from the former I have it Avith 6 whorls, Diam. 

 maj. 24, min, 22, Alt. 10 mill. In both of those States indi- 

 viduals are found of nearly uniform color, from pale straw to 

 dark reddish brown. In Canada, on Goat Island, Niagara, and 

 on Cunningham Island, Lake Erie, the shell is frequently much 

 elevated, even globose, thickened, and almost covered with dark- 

 colored flam mules. 



A beautiful variety was discovered a few years ago by Mr, 

 Ferguson on the Helderberg Mountains, New York; subse- 

 quently near Greenwood Cemetery, Long Island ; and also in 

 the woods adjoining the New York Bay Cemetery, near Jersey 

 City. It is small, comparatively smooth, especially at the base, 

 has a shining somewhat translucent epidermis, which on dead 

 shells becomes opaque. The suture is well impressed and the 

 outer whorl is not, as usual in the species, obsoletely carinated. 

 The deep red flammules are disposed with much regularity on 

 a pale horn-colored ground. An average sized specimen, with 

 5 whorls, is Diam. maj. 15|^, min. 14, Alt. 6^ mill. The ani- 

 mal does not exude the saffron-colored mucous secretion usually 

 observed in the typical form. I designate this shell as II. alter- 

 nata Say va7\ II. Fergusoni. 



In Tennessee, North and South Carolina, and Georgia, 

 the moderately elevated and numerous striae of II. alter- 

 nata are replaced by sharply defined distant ribs. In a spe- 

 cimen from North Carolina, for which I am indebted to Mr. 

 David Christy, these ribs have a remarkable development, being 

 nearly 1 mill, apart on the last whorl ; the shell is depressed, 

 but obsoletely carinated only. Bishop Elliott found a few spe- 

 cimens on the eastern slope of the Cumberland Mountains, 

 strongly ribbed, depressed, and the last whorl subcarinate, the 



