THK NAUTILUS. 107 



SOME ZONITIDiE COLLECTED BY J. H. FERRISS IN ARKANSAS AND 

 THE CHOCTAW NATION. 



BY HENRY A. PILSBRY. 



Some account of shells collected by Mr. J. H. Ferriss in Arkansas 

 and Choctaw Nation was published in The Nautilus for August 

 of this year. A series of Zonitida collected at the same time affords 

 some interesting data. Vitrea simpsoni (Pils.) was taken at Poteau, 

 in the eastern pari of the Choctaw nation on Poteau river, near the 

 State of Arkansas. It resemble- V. capsella, but differs in the tri- 

 angular forfn of the aperture. 



Gastrodonta demissa, typical, was taken in Arkansas near Texar- 

 kana, ami at Tushkahomma and Poteau in the Choctaw Nation. 



At both Tushkahomma and Poteau a form having the characteris- 

 tic lens-shaped contour, brilliant gloss and basal striation of demissa 

 occurred, differing from demissa in having a long and strong lamella 

 within, like the outer lamella of G. gularis. There is no trace of an 

 inner or columella!- lamella, such as gularis and suppressa generally 

 show, and the general form of the shell is entirely that of demissa, 

 quite unlike suppressa. The umbilicus i- a -mall round puncture, as 

 of a pin stuck through a sheet of paper, quite as in typical demissa ; 

 and the periphery i- subangular. In G. suppressa the periphery is 

 well rounded and the umbilicus larger. Tin.- variety may lie called 

 var. lamellata. It is most interesting as connecting the gularis group 

 with the //(/era group of GastrodontS. 



The form I described some years ago as Zonites brittsii, from Hot 

 Springs, Ark., belongs also to demissa, from which it differs in the 

 imperforate axi>. and very slight excavation of the base in the center. 



A NEW AMERICAN LAND SHELL. 



BY HENRY A. PILSBRY. 



Polygyra uvulifera bicornuta n. v. 



Shell differing from the typical P. uvulifera (the type locality of 

 which is Long Key, above mouth of Sarasota Bay), in being less de- 

 pressed, the last whorl strongly grooved within the umbilicus, the 

 aperture everywhere more contracted ; parietal margin of the peri- 

 stome strongly elevated, produced in two erect processes or " horns," 

 one at the junction of outer lip and parietal lip. another upon the pari- 

 etal lip near its inner termination, situated like the corresponding lobe 



