POLYGYRA. 285 



abruptly contracted, becoming narrower above, and flattened and slightly stri- 

 ated beneath, but again, as it passes towards and beneath the aperture, dilated 

 and convex. This change of form gives to the last whorl a distorted appear- 

 ance. The internal lamina is on the columellar wall of the contracted and 

 flattened portion of the last whorl, and runs obliquely, in the direction of the 

 aperture, attaining a length in a large specimen of about 6 mill. The charac- 

 ter of the aperture is most like that of cereolus, but in that species the last 

 whorl has none of the peculiarities above described. The internal lamina is 

 found in a majority of specimens, but not in all; it can generally be seen 

 through the outer wall of the shell. 



The upper figure is engraved directly from a photograph on wood. 



Jaw as usual in the genus; over 12 ribs. One jaw examined has a decided 

 median projection. 



Lingual membrane with 22 — 1 — 22 teeth, of which 9 are laterals, the tenth 

 tooth having its inner cutting point bifid (PI. VI. Fig. M). 



I can now state that cereolus, Carpenleriana, septemvolva, volvoxis, and Febi- 

 geri have the same dentition. In all, the splitting of the inner cutting point 

 commences at the tenth tooth. The species also agree in their genitalia. 



Genitalia as in P. septemvolva. 



Polygyra Febigeri, Bland. 



Shell umbilicate, orbicular, flat, thin, shining, pale or reddish horn-colored, 

 with rather distant rib-like striae above, finely striated beneath; spire almost 

 level; suture deep; whorls 5^ to 6, rather convex, regularly increasing, the 

 last angular at the periphery, inflated below ; umbilicus funnel-shaped ; aper- 

 ture oblique, kidney-shaped ; peristome thickened, little reflected, the margins 

 joined by a strong triangular callus. Greater diameter 8|, lesser 7£ mill. ; 

 height, 3£ mill. 



Helix Febigeri, Bland, Am. Journ. Conch., II. 373, PI. XXI. Fig. 10 (1866). — 



W. G. Binney, L. & Fr.-W. Sh., I. 108, Fig. 184 (1869). 

 Polygyra Febigeri, Tryon, Am. Journ. Conch., III. 160 (1867). Fig. 183. 



New Orleans ; Mobile. A species of the Southern Region. 



This species certainly differs from P. cereolus, Muhl., septem- 

 volva, Say, volvoxis, Parr., and Carpenteriana, Bid., the four 

 species of the same group hitherto found on the North Ameri- 

 can continent. Compared with paludosa, Pfr., of Cuba, the 

 rib-like striae are more regular and prominent, it is more de- 

 cidedly angular at the periphery, and the form and armature of P. Febigeri. 

 the aperture are different. In Febigeri there is no such exca- 

 vation below the angle of the periphery as prevails, more or less, in the other 

 above-named continental species. In this respect, and in the form of the 

 aperture, Febigeri appears to be most nearly allied to microdonta, Desh., of 



