PILSBRY: non-marine MOLLUSCA of PATAGONIA. 6oi 



and weak at the base. The aperture is quite oblique, ovate, subangular 

 above. The outer lip is thick within. The columellar margin is some- 

 what straightened, the columella very wide, flattened and excavated, a 

 rather deep furrow running parallel with and near to the inner edge. 



Length 5, diam. 4.9 mm. 

 4.9 " 4.6 " 



Uruguay River, at Paysandu, Uruguay. Types, No. 69,698, A. N. S. P. 



Development. — The youngest individuals seen have y/^ whorls, with a 

 length of 2.3 and diam. of 2.8 mm. They are therefore more depressed 

 than the adult stage, and have both green bands well developed. The 

 subsutural green band begins at the end of the second or beginning of 

 the third whorl. The axis is wholly imperforate. The columella is very 

 broad, half-round, with the excavation in its face deeper than in adults. 

 At no stage are there any traces of carinae or protuberances. 



I have seen a long series of this species. The characters described 

 above are very uniform, and it is readily known by the Naticoid shape, 

 grooved columella and green bands. Named in honor of Dr. H. von 

 Ihering. 



POTAMOLITHUS PHILIPPIANUS Sp. nOV. 

 (Plate XLI<5, Figs, i, \a,i) 



The shell is globose, solid and strong, light greenish yellow, with a 

 narrow dark green border below the suture, the apex pinkish. The surface 

 is nearly smooth, showing faint growth-lines and fine, very indistinct 

 spiral striae. Spire low, conic, the apex minute, entire. Whorls 43^ , 

 convex, the last not more rapidly descending, distinctly flattened periph- 

 erally, shouldered above the flattened zone, very obtusely subangular 

 below it, the base convex, with a rather wide, concave and crescentic 

 columellar area, the lower portion of which is bounded by an angle. The 

 outer lip is strengthened by a moderately high varix near the margin, much 

 lower at the base, and continuous with the angle bounding the columellar 

 area. The aperture is very oblique and semicircular, the outer margin 

 being deeply arcuate, the inner somewhat straightened. The columella is 

 rather broad, with a shallow furrow on its face ; and the outer edge is 

 somewhat elevated near the insertion, leaving, in the type specimen, a 

 shallow crevice behind it, not visible in younger shells. 



Length 5.7, diam. 5.7 mm. 



