344 THE CHICAGO ACADEMY OF SCIENCES. 



Limnoea zebra TRYON, Amer. Journ. Conch., I, p. 228, pi. 23, fig. 4, 1865; 

 Amer. Journ. Conch., Ill, p. 196, 1867. CURRIER, Kent. Sci. Inst., Mis. Pub., 

 No. 1, 1868. TRYON, Con. Hald. Mon., p. 94 (68), pi. 16, fig. 14, 1872. CALKINS, 

 Cin. Quart. Journ. Sci., 1, p. 243, 1874; Cin. Quart. Journ. Sci., 1, p. 323, 1874. 

 TRYON, Home & Science Gossip, June 15, 1881. MARSH., Conch. Exch., II, p. 

 104, 1887. SNYDER, The Museum, III, p. 12, 1896. 



Limnophysa zebra CURRIER, Amer. Journ. Conch., I, p. 294, 1865. TRYON, 

 Amer. Journ. Conch., I, pp. 68, 70, 250, 1865. CALL, Bull. Wash. Coll. Lab. 

 N. H., I, p. 53, 1885. KEYES, Bull. Essex Inst., XX, p. 70, 1888. 



Limnea reflexa var. zebra WITTER, Quart. Journ. Conch., I, p. 386, 1878. 

 WALKER, Journ. Conch., II, p. 330, 1879. 



Limnophysa renexa var. zebra DECAMP, Kent. Sci. Inst., Mis. Pub., No. 5, 

 p. 8, 1881. 



Limnaa reHexa zebra WALKER, Nautilus, VI, p. 32, 1892; Rev. Moll. Mich., 

 p. 7, 1894. SARGENT, Nautilus, IX, p. 127, 1896. 



SHELL: Elongated, attenuated, thin; periostracum light corneous 

 or honey-yellow, sometimes streaked zebra-like ; surface dull to shining, 

 growth lines distinct, crowded, crossed by numerous very fine incre- 

 mental striae; nuclear whorls l^J, small, similar to those of palustris 

 in outline, light corneous to very dark brown in color; whorls six to 

 seven, very flat-sided, the last a little over one-third the length of the 

 entire shell ; spire long and very acutely attenuated, forming an almost 

 unbroken, acute triangle in typical specimens; sutures impressed, fre- 

 quently margined below by a white band edged with chestnut ; aperture 

 elongate-ovate, narrow, oblique, slightly contracted at the upper part; 

 rounded at the lower part ; peristome sharp, thin, a rather heavy callus 

 within which is dark chestnut colored, the remainder of the aperture be- 

 ing brownish or horn color ; this color shows on the outside as a light 

 band in many specimens ; inner lip very narrow, erect, reflected over the 

 umbilicus, completely closing it ; the callus on the parietal wall is well 

 marked and is so heavy in some specimens, especially when slightly 

 raised, as to render the aperture continuous ; the axis is slightly twisted, 

 frequently somewhat gyrate. 



Length. Width. Aperture length. Width. 



37.00 11.50 14.00 6.25 mill. Type exilis. 



37.00 11.00 14.00 6.00 " Chicago. 



28.00 9.50 12.00 4.50 " Type zebra. 



30.00 9.00 13.00 5.00 " Chicago. 



24.00 7.50 10.50 4.50 " 



28.50 7.50 11.50 4.50 " 



28.00 7.50 11.00 5.00 " Mercer Co., 111. 



33.00 9.50 12.50 5.50 " Winnebago Co., 111. 



36.50 10.00 15.00 6.50 " " " 



28 -00 9-00 13.00 5.50 " Antrim Co., Mich. 



39.00 11.00 16.00 6.00 " Minneapolis, Minn. 



30.10 9.10 12.1" 4.00 " Poland, Ohio. 



