THE NAUTILUS. 23 



Physa gyrina elliptica Lea. Fig. 6. 



Physa elliptic a LEA, Trans. Amer. Phil. Soc., vol. V, p. 115, pi. 

 xix, tig. S3, 1837. Physa anrea LEA, I.e., vol. VI, p. IS, pi. 

 xxiii, tig. 100, JS39. Physa troostiana LEA, Proe. Am. Phil. Soc., 

 vol. II, p. 32, 1S41. Physa nicklinii LEA, Proc. Phil. Acad. Sci., 

 p. 114, 18G-1. Physa altonensis LEA, I.e., p. 114 18G4. Physa 

 felrigerii LEA, I.e., p. 114, 1SG4. Physa oleacea TUYON, Amor. 

 Journ. Concli., vol. II, p. G, pi. ii, Hg. G, 186G. 



Shell differing iroin typical gyrina in being 

 more elliptical, having a shorter, more rounded 

 spire, and hence more convex whorls, the 

 spire, as described by Tryon, " with the outline 

 not elevated above a continuation of the general 

 curve of the body." The shell is also more 

 solid and the outer lip thicker with a very heavy, 

 bluish-white callus. The surface sculpture is the same as in gyrina. 



Length 15.00 ; width 7.50 ; aperture length 9.50 ; width 3.50 mill. 



Length 11. 00; width G. 00; aperture length 7.00 ; width 2.50 mill. 



Length 12.00 ; width 7.50 ; aperture length 9.00 ; width 3.75 mill. 



Animal, jaw, and radula, as in gyrina. Distribution: evidently 

 the same as gyrina. Geological distribution : Pleistocene ; Loess. 

 Habitat : Almost always associated with gyrina. 



Remarks : The typical form of this variety seems at first quite 

 distinct from gyrina, but in a multitude of forms (the writer has ex- 

 amined several thousand specimens) is seen to fade imperceptibly 

 into the typical form. From observations in the present area, gyrina 

 would seem to be dimorphic, consisting of the typical gyrina with 

 long spire, and the variety elliptica with short, dome-shaped spire. 

 This belief is strengthened by the fact that the two forms are always 

 associated together. It is not quite as common as the typical form. 



Physa Integra Ilaldeman. Fig. 7. 



Physa integra HALDEMAN, Mon. p. 33, pi. IV, h'g. 7, 8, 1841. 

 Physa niagarensis LEA, Proc. Phil. Acad. Sci., p. 114, 18G4. 



Shell oval, whorls 4^-5 ; spire short, pointed, the whole convex ; 

 sutures well marked, sometimes banded by a faint white line; color 

 varying from light yellowish horn to pale brown ; sculpture as in 

 gyrina, the lines being very deep and the wrinkled edges very 

 convex ; protoconch consisting of one and a half smooth, rounded, 

 wine-colored whorls ; aperture oval, rather wide, produced at the 



