THE NAUTILUS. 81 



A LIST OF SHELLS FROM NEBRASKA. 



BY BRYANT WALKER. 



The shells enumerated in the following list were all collected hy 

 Dr. R. H. Wblcott, of the University of Nebraska, Lincoln, Neb. 



Many of the localities represented are in counties not covered by 

 Aughey's List (Bull. U. S. Geol. Survey, 18, p. 697), so that while 

 not large, the collection makes a considerable addition to our knowl- 

 edge of the distribution of the different species in the State. 



Dr. Pilsbry has kindly identified the Vertigo and Biftdaria. 



Polygyra profunda Say. Omaha. 



Polygyra midtilineata Say. 



Polygyra midtilineata alba Witter. 



Polygyra midtilineata rubra Witter. 



Omaha. A rather small, solid and elevated form. The four 

 specimens measure 20^ x LH, 20§ x 15, 20 x 1.5^, 20\ x 14 mm. 



Bellevue. A single, small, globose, greenish-brown, unicolored 

 specimen measuring 16§ x 124. mm. 



Polygyra fraterna Say. Omaha. A small elevated, perforate 

 form varying from 12|-13^ x 4|-5| mm. Salt Creek, Roca. Simi- 

 lar in shape, but rather larger, 13-14 x 5—5^ mm. 



Bifidaria contractu Say. Roca. 



Bijidaria pentodon tuppaniana Ad. Monroe Canyon, Sioux Co. 



Vertigo ovata Say. Monroe Canyon. 



Vitrea hammonis Strom. Roca. 



Euconulus cher sinus polygyratus Pils. Omaha, Roca and Monroe 

 Canyon. 



Zonitoides arborea Say. Lincoln, Roca and Monroe Canyon. 



Pyramidula cronkhitei anthonyi Pils. Monroe Canyon. 



Vallonia parvula Sterki. Roca. 



Succinea grosvenori Lea. Salt Basin, Lincoln. A small, rather 

 thick-shelled form, largest specimen 10x8 mm. 



Hackberry Lake, Cherry Co. A large, thin-shelled form, quite 

 variable in contour, the two largest specimens measuring 14|x 104^, 

 aperture 7^x11 and 15^x10, aperture 7x10 mm. Immature 

 shells are very similar to those from Lincoln, but more inflated. 



Succinea retusa Lea. Hackberry Lake and Marsh Lake, Cherry 

 County. 



Succinea avara Say. Roca and Monroe Canyon. 



