354 



THE CHICAGO ACADEMY OF SCIENCES. 



Limnaa subulata BINNEY, Check List, p. 12, 1861; L. & F.-W. Sh. N. A., 

 II, p. 42, fig. 54, 1865; Journ. de Conoh., XV, p. 427, 1867. 



SHELL: Elongated, turreted, narrow, thin; periostracum yellow- 

 ish to reddish horn; surface shining, marked by close set lines of 

 growth which are crossed by fine, wavy, impressed spiral lines; the 

 growth lines are sometimes raised into fine ridges, especially on the 

 last whorl; nuclear whorls 1^2, smooth, round, dark colored, in out- 

 line like those of reflexa; whorls 6-7^, regularly increasing, flat-sided; 

 spire long and attenuated; sutures not deeply impressed, sometimes 

 bordered by a white line ; aperture ovate, oblique, somewhat expanded 

 in some specimens ; peristome thin, the internal rib scarcely developed ; 

 inner lip narrow, reflected over and nearly closing the umbilicus, leav- 

 ing a small chink ; parietal callus wide and tightly appressed to the body 

 whorl; columella with a distinct, strong, ascending plait; the aperture 

 is sometimes a little reflexed as in some forms of refle.va; the axis is 

 twisted. 



mgth. Width. Aperture lengtf 



9.00 

 9.50 

 10.50 

 9.00 

 7.00 

 10.00 

 8.00 

 13.00 

 12.50 



TYPES : Attenuata, Academy of Natural Sciences, Philadelphia, 

 two specimens, No. 58572. Subulata, turritus and mexicanus, location 

 not ascertained. 



TYPE LOCALITY: Attenuata, Mexico City; subulata, Zimapan, 

 Hidalgo; turritus and mexicanus, Mexico. 



ANIMAL, JAW, RADULA and GENITALIA : Not examined. 



RANGE: Mexican plateau. This species is found in the Lower 

 Austral and Upper Austral life zones. 



RECORDS. 



HIDALGO: Zimapan (Dunker). 



MEXICO: Lake Chalco, City of Mexico (Baker; Heilprin; Strebel) ; Uhde, 

 Lake of Mexico (Dunker) ; City of Mexico (Deppe and Schiede; Say) ; Lagos 

 de Tezcuco, City of Mexico (Phil. Acad.) ; Tlalpam, City of Mexico (Pilsbry; 

 Rhoads). 



GEOLOGICAL DISTRIBUTION : Unknown. 



ECOLOGY: Attenuata lives along the ( shores of the shallow lakes, 

 in water from a few inches to a foot or more in depth ; the shells are 

 usually found on the muddy bottom or in shore vegetation. 



