POLYGYRA. 281 



In the region of the Rio Grande, both in Texas and Tamaulipas. A species 

 of the Texan Subregion. 

 Animal not observed. 



Polygyra septemvolva, SAY. 



Shell broadly umbilicated, subcarinated, discoidal, F j g . 



russet horn-color, with stout striae above, smooth be- 

 low ; plane above, with 7 (sometimes 8|) or less flat- 

 tened whorls; equally plane below, with 3^ full, more 

 convex whorls on a level, then ending in a deep, per- 

 vious umbilicus, the penultimate somewhat overlapped 

 by the last, the antepenultimate much the largest; 

 aperture very oblique, remote from the axis, subreni- 

 form, constricted behind the peristome ; peristome 

 thickened, bluntly reflected, continuous, its termina- 

 tions joined by an elevated, heavy, tooth-like triangular 

 fold. Greater diameter 15, lesser 13 mill.; height, 4 mill. 



Polygyra septemvolva, SAY, Journ. Acad. Nat. Sci. Phila., I. 278 (1818) ; Nich. 



Encycl., 3d ed. (1819); BINNEY'S ed. 11. TRYON, Am. Journ. Conch., III. 



159 (1867). 

 Helix septemvolva, BINNEY, Terr. Moll. U. S., II. 196 (part), PI. XXXVIII. outer 



Figs. ; P1.XXXIX. Fig. 1. DEKAY, N. Y. Moll., 47 (1843). BLAND, Ann. 



N. Y. Lye., VII. 131, Fig. on p. 136. W. G. BINNEY, Terr. Moll., IV. 89, 



part ; L. & Fr.-W. Sh., I. 104 (1869). PFEIFFER, V. 419 (1868). 

 | ? Helix volvoxis, PFEIFFER, see below. 



St. Augustine, Florida. Confined to the Florida Subregion. 



Animal (sec p. 262) brownish, eye-peduncles darker, very long and slender, 

 eyes black ; foot narrow, thin, semi-transparent, receiving its color, in some de- 

 gree, from the substance on which it is placed, not projecting behind the shell 

 when in motion ; length less than twice the breadth of the shell, which it car- 

 ries nearly horizontal. 



The shell described and figured above, which is, no doubt, the form called 

 septemvolva by Say, is only found, to my knowledge, at St. Augustine, Flor- 

 ida. 1 There are, however, associating with it there, and also found at many 

 other points on the Georgia, Florida, and Alabama coasts, other forms which 

 appear to be varieties of it. It may be said, therefore, that it varies in being 

 occasionally a little convex, more or less carinate, and in exhibiting a greater 

 or less number of full volutions on the base. The lower surface is sometimes 

 marked with the alternate white and brown flammules which characterize P. 

 Carpenteriana. 



The reflected peristome in this shell seems to be formed at various periods 



1 Recently specimens have been received from Key West. 



