THE NATURAL HISTORY SURVEY. 315 



This species is very variable in this region, some forms 

 approaching ampullacea Gould, while others might be taken for 

 gabbi Tryon or virginea Gould, so far as form goes. It is prob- 

 able that some west coast names will be added to the above 

 synonymy, when more study has been given to this genus. 

 This species is a triannuan. 



1273. Physa gyrina var. elliptica Lea, pi. xxxiv, fig. 5. 



Physa elliptica LEA, Trans. Amer. Phil. Soc., Vol. V, p. 115, pi. xix, fig. 



83, 1837. 



Physa aurea LEA, 1. c., Vol. VI, p. 18, pj. xxiii, fig. 106, 1839. 

 Physa troostiana LEA, Proc. Amer. Phil. Soc., Vol. II, p. 32, 1841. 

 Physa nicklinii LEA, Proc, Phil. Acad. Sci., p. 114, 1864. 

 Physa altonensis LEA, 1. c., p. 114, 1864. 

 Physafebigerii LEA, 1. c., p. 114, 1864. 



Physa oleacea TRYON, Amer. Journ. Conch., Vol. 1 1, p. 6, pi. ii, fig. 6, 1866. 

 Physa elliptica minor CRANDALL, The Nautilus, Vol. XV, p. 55, 1901. 



Shell: Differing from typical gyrina in being more ellip- 

 tical, having a shorter, more rounded spire, and hence more 

 convex whorls, the spire, as described by Tryon, "with the out- 

 line 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. (8504.) 

 11.00; " 6.00; " " 7.00; " 2.50 " (8504.) 



12.00; " 7.50; " " 9.00; " 3.75 " (8502.) 



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 examined several thousand specimens) is seen to 

 fade imperceptibly into gyrina. 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-like 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. 



128. Physa Integra Haldeman, pi. xxxiv, fig. 6. 



Physa integra HALDEMAN, Mon., p. 33, pi. iv, figs. 7, 8, 1841. 



Shell: Oval, whorls four and one-half to five; spire short, 



