HELIX, 105 



Polygyra septemvolva, Say, Joiirn. Acad. Nat. Sci. Pliilad. I, 278 (1818) ; 



Nich. Encycl, 3d ed. (1819) ; Bixney's ed. 11. — Tryon, Am. Journ. 



Conoh. Ill, 159, pi. xi, f. 22 (18(J7). 

 Helix septemvolva, Binney, Terr. Moll. U. S. II, 19G (part), pi. xxxviii, 



outer figs. ; pi. xxix, f. 1.— DeKay, N. Y. Moll, 47 (1843).— Bland, 



Ann. N. Y. Lye. VII, 131, f. on p. 136.— W. G. Binney, Terr. Moll. 



IV, 89, part. 

 ? Helix volvoxis, Pfeiffer, see below. 



St. Augustine, Florida. 



Animal (see p. 86) brownish, eye-peduncles darker, very long 

 and slender, eyes black ; foot narrow, thin, semi-transparent, 

 receiving its color, in some degree, 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 carries 

 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, Florida. 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 ex- 

 hibiting 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 H. carpenteriana. 



The reflected peristome in this shell seems to be formed at 

 various periods of growth, thus creating a greater diversity of 

 size in the apparently mature shell than exists in any other 

 species. From the nucleus until the accomplishment of five 

 full whirls, each whirl on the base is curved a little lower than 

 that which precedes it ; and up to this time, consequently, the 

 umbilicus is deep and gradually expanding, exhibiting, when 

 carefully examined, all the volutions. Up to this period, also, 

 the spire is almost always prominent. After five whirls are com- 

 pleted, the succeeding ones usually follow in the sanre horizontal 

 plane, and give a discoidal character to the shell. It is manifest, 

 therefore, that specimens in each of these stages must present 

 considerable difi"erences ; and, accordingly, the small, delicate 

 shell, having a slightly convex spire of five whirls, a deep um- 

 bilicus, and a transverse diameter of only one-eighth of an inch, 



