PILSBRY: NON-MARINE MOLLUSCA OF PATAGONIA. 573 



e 3 . Three-banded with reddish ; alt. 4, diam. 3 mm. Parana River. 



P. petilianns. 

 d l . Columella and especially the parietal wall thick, forming a blackish ledge ; 



spire very short. 

 e. Last whorl swollen below the suture ; olivaceous, about 5x4 mm. 



P. paysanduamis. 



e 1 . Last whorl evenly rounded ; olive with black markings, alt. and 

 diam. 7 mm. p. doeringi. 



d 2 . Columella wide, flat and white ; last whorl evenly rounded. 



e. Pale green, diameter nearly equal to the alt, 3 x 2.8 mm. P. agapctus. 

 e l . Pale green, higher than wide, alt. 3, diam. 2.5 mm. P. chloris. 



e 2 . Olivaceous, perforate, alt. 5.7, diam. 4.3 mm. P. catharina. 



e 3 . Reddish brown, alt. 3.5, diam. 3.4 mm. P. ribeirensis. 



e*. Naticoid, but with an obtuse prominence on the columella far within. 



P. intracallosus. 



d*. Last whorl noticeably flattened peripherally ; solid, brown, becoming 



green at the base and behind the lip ; 6 x 5.6 mm. P. jac uhyensis. 



c 1 . Acutely long-ovate in shape, smooth, the ovate aperture not much exceeding 



half the total length; 4.3 x 3 mm. P. simplex. 



a 2 . Outer lip sinuous, nicked or notched. 



b. Trochiform, the periphery very strongly carinate, aperture squarish, umbilical area 



large. P. filipponei. 



V. Shell nearly globular, the diameter about equal to the alt, smooth, swollen below 



the suture, lip with a sinus above. P. paysanduanus sinulabris. 



P. Shell globose-conic. 



c. Outer lip strongly expanded, with swollen, thickened and three-notched face. 



P. sykesi. 



c l . The outer lip thin, with deep subsutural and basal sinuses; 4.8 x 3.3 to 

 5 x 3.9 mm. P. bisinuatus. 



(?. Similar, but with the sinuses shallower, the upper one often inconspicuous. 



P. bisinuatus obsolctus. 



Jf. Shell acutely ovate-conic, about 4.3 x 2.7 mm., the outer lip thin, sinuated, especially 

 ,at the base. P. gracilis. 



GROUP OF P. BISINUATUS. 



Smooth, globose-conic or ovate-conic species, with no trace of spiral 

 angles or sulci, except in P. filipponei ; the outer lip usually sinuous. The 

 spire is longer than in other groups of the genus. 



POTAMOLITHUS FILIPPONEI VOn Ihering. 

 (Plate XLIrt, Figs. 8, 8a.) 



Potamolithus filipponei von Ihering, Nautilus, XXIV, June, 1910, p. 15. 



The shell is imperforate, pyramidal, olive colored, with a weak reddish- 

 brown spiral band in the middle of the penultimate whorl. Surface 





