1896.] NATURAL SCIENCES OF PHILADELPHIA. 561 



NEW SPECIES OF FRESH WATER MOLLUSKS FROM SOUTH AMERICA. 



BY HENRY A. PILSBRY. 



The forms described below were encountered in the course of 

 identifying a series of mollusks collected by Dr. Wm. H. Rush, U. 

 S. N., in Uruguay and Argentina, a list of which will be found in 

 The Nautilus for November of this year. To the forms collected by 

 Dr. Rush have been added several others,- apparently undescribed, 

 from the collection of the Academy of Natural Sciences of Philadel- 

 phia, 



To the above-mentioned paper in The Nautilus the reader is re- 

 ferred for some account of the localities represented by specimens 

 here described, and for notes on the species associated with them, 



CHILINIDiE. 



Chilina RusMi n. sp. PI. XXVI, fi^s. 6, 7. 



Shell oval, strong, yellowish-olivaceous with five girdles of dusky, 

 narrow spots alternating with lighter ones. Spire produced, ter- 

 raced, but flat-topped, the whorls strongly keeled around the shoul- 

 der, flat above the keel. Aperture long-ovate, white with chestnut 

 spots inside ; outer lip thin ; columellar lip white, callous, with a 

 strong, acute entering fold at the root, and a very inconsijicuous fold 

 in the middle ; the parietal wall with a strong entering fold which 

 is abrupt below, and filled in above with a heavy callus. 



Alt. 16, diam. lOj mm. ; alt. of aperture 12 mm. 



Uruguay River at Fray Bentos (Dr. Rush !). 



The conspicuously angular spire is a peculiar feature of this shell. 

 The apex is considerably eroded, so that the number of whorls can- 

 not be stated. 



LIMW^IDJE. 

 Planorbis castaneonitens Pilsbry &, Vanatta, n. sp. PI. XXVII, figs. 10, 11, 12. 



Shell- thin, chestnut brown, very smooth and glossy; growth-striae 

 light ; right and left sides showing 4 whorls, about equally and 

 quite shallowly concave ; spire on right side less than half the 

 diameter of shell, inner 1 h whorls more sunken ; spire on left side 

 decidedly wider than on the right. Last whorl wide on the right, 



