107 



CHARACTERS OF THREE NEW SPECIES OF FRESHWATER 

 SHELLS FROM URUGUAY. 



By H. B. Pkeston, F.Z.S. 



Read 12th Ai^ril, 1912. 



Hydeobia Adamsi, u.sp. 



Shell fusiform, thin, pale greenish straw-colour; remaining whorls 



6J, flattish, showing traces of spiral strite, especially on the last 



whorl, and marked with transverse lines of growth ; suture impressed, 



margined above ; umbilicus very narrow, deep ; columella descending 

 in a curve, slightly reflexed ; peristome continuous, simple ; aperture 

 ovate. Alt. 6-75, diam. maj. 3 mm. ; aperture, alt. 2-5, diam. 1 mm. 

 Hah. — Monte Video (L. E. Adams). 



Planorbis levistriatus, u.sp. 

 Shell sub-orbiculai", moderately thin, pale brownish horn-colour; 

 spire concave ; whorls 5|, marked with very oblique, arcuate, 

 transverse lines of growth, and sculptured with very fine, closely set, 

 wavy, spiral strife, the last whorl not descending ; suture deeply 

 impressed ; umbilicus very wide, shallowly depressed ; labrum thin, 



• 



acute, the upper margin projecting considerably beyond that of the 

 lower, both margins joined by a thin, whitish, pearly callus ; aperture 

 very broadly sublunate. Alt. 4*5 mm.; diam. maj. 14, min. 11 mm. ; 

 aperture, alt. 4-25, diam. 5 mm. 



Hab. — The Miguelete River, Monte Video (L. E, Adams). 



Planorbis Uruguatensis, u.sp. 

 Shell discoidal, thin, semi-transparent, pale yellowish horn-colour ; 

 spire concave ; whorls 6, shining, marked with lines of growth ; suture 

 rather deeply impressed ; base of shell concave ; labrum thin, acute, 



the margin diffusing into light whitish callosities which do not unite ; 

 aperture broadly luuate. Alt. 1'75, diam. maj. 7 mm.; aperture, 

 alt. 1"75, diam. 1-25 mm. 



iZrtJ.— Monte Video (L. E. Adams). 



