THK NAUTILUS. 107 



SOME ZONITID.E COLLECTED BY J. H. FERRISS IN ARKANSAS AND 



THE CHOCTAW NATION. 



BY II-EXHY A. PILSBRY. 



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

 and Choctaw Nation was published in TIIK NAUTILUS for August 

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

 some interesting data. I'ifrea xftnj>soiu (Pi Is.) was taken at Poteau, 

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

 State of Arkansas. It resembles V. capsefla, but differs in the tri- 

 angular form of the aperture. 



Gastrodonta demissa, typical, \vas taken in Arkansas near Texar- 

 kana, and at Tushkahomma and Poteau in the C'lioctaw Nation. 



At both Tushkahomma and Poteau a form having the characteris- 

 tic lens-shaped contour, brilliant gloss and basal slriation of <l<'ntissa 

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

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

 inner or columellar lamella, such as yufaris and sup/iri's^n generally 

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

 quite unlike suppress*!. The umbilicus is a small round puncture, as 

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

 and the periphery is subaugular. In G. snppressa the periphery is 

 well rounded anil the umbilicus larger. This variety may be called 

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

 with the ligera 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 axis, and very slight excavation of the base in the center. 



A NEW AMERICAN LAND SHELL. 



BY IIEN'UY A. PILSBUY. 



Polygyra uvulifera bicornuta n. v. 



Shell diH'ei-ing from the typical P. urulifera (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 Up near ifs inner termination, situated like the corresponding lobe 



