HELIX. 



185 



Helix polychroa, Binkey, Terr. Moll. II, 123, pi. xlvi ; xlvii. 



Pohjmiia varians, Tkyon, Am. Journ. Conch. II, 321, pi. vi, f. 9-13 (1866). 



Fig. 325. 



Key West, Key Biscayne, Cape Florida. Also at New Provi- 

 dence. 



Jaw* strongly arched ; ends attenuated, pointed ; 

 anterior surface smooth ; concave margin simple, 

 with an obtuse, median projection. 



Lingual dentition as in Helix alternata, monodon, 



say a, &C. Helix variaiis. 



Subgenus AMPELITA, Beck. 



Shell broadly umbilicated, depressed, orbicular; whirls 4-5, 

 the last more or less angulated or carinated, falling before, convex 

 at base, angularly passing into a spreading umbilicus ; aperture 

 lunately-elliptic or irregularly rhomboid ; peristome reflected, 

 its terminations approaching, usually joined by callus. 



Fig. 326. 



Helix rO"^;veBlli, Newcomb. — Shell broadly iimbilicated, orbicular, 

 depressed, opaque white, with a revolving chestnut 

 baud, polished, very finely obliquely striate, hirsute ? or 

 granulated; whirls 4i, convex, the last large, flattened, 

 anteriorly descending ; spire but little elevated, at the 

 apex projecting like a nipple ; suture moderately 

 marked ; aperture very oblique, truly circular ; peri- 

 stome thin, slightly reflected, margins approximated, 

 continued by callus adhering to the parietal wall of the 

 aperture. Greater diam. 20, lesser 15 ; height 7 mill. 



Helix rowelli, Newcomb, Proc. Cal. Acad. Nat. Sci. Ill, 



181 (1865). 

 Aglaja roweUii, Tryon, Am. Journ. Conch. II, 316, pi. Helix rowelli 



xi, f. 30 (1867). 

 Helix lohrii, Gabb, Am. Journ. Conch. Ill, 236, pi. xvi, f. 2 (1867). 



' The same style of jaw exists in Helix microphysa, albersiana, and clis- 

 ciilits, but not in Ildix muscarum. 



