Lymnoea.] GASTROPODA. 605 



Protoconch small, obtuse, mostly eroded. Whorls 4, gradually increas- 

 ing, flatly convex, tlie last high, slightly ventricose ; base convex. 

 Suture deep. Aperture ovate, angled above, rounded below. Outer 

 lip broadly convex, thin and sharp. Basal lip more narrowly rounded. 

 Columella subvertical, straight, inconspicuously twisted. Inner lip 

 narrow, reflexed over the pillar, leaving a small umbilical chink, very 

 thin on the lightly convex parietal wall. 



Diameter, 4 mm. ; height, 7-5 mm. ; aperture, 3 mm. by 4-5 mm. 

 Diameter, 5 mm. ; height, 9-5 mm. (Birch Hill Lagoon specimen). 



Dentition (Suter, T.N.Z.I., xxiv, 300, pi. 23, f. 55, 56). Jaw consist- 

 ing of three pieces. Formula of radula 90 x 16 + 5 + 1 + 5 + 16. 

 Central tooth small, bicuspidate ; laterals quadrangular, with 2 cutting- 

 points ; marginals tridentate. 



Type in my collection. 



Hob. Creek near Governor's Bush, Hooker Valley, type (A. 

 Suter) ; lagoon at Birch Hill Station, Tasman Valley (H. S.) : lake 

 on Arthur's Pass ; Ashburton (W. W. Smith). 



2. Lymnoea leptosoma, Hutton, 1885. Plate 24, fig. 11. 



Limncea leptosoma, Hutt., T. N.Z.I., xvii, 1884 (1885), 55, pi. 12, f. 3; 

 Hedley and Suter, P.L.S. N.S.W. (2), vii, 625 ; Suter, J. de Conch., xli, 

 1893 (1894), 230. 



Shell small, ovate, acuminate above, glossy, fairly solid, horny. 

 Sculpture consisting of 4 or 5 obsolete distant spiral ridges on the 

 body-whorl, and rather strong axial striae. Colour pale-horny, with 

 indications of darker spiral bands near the aperture. Epidermis 

 thin, slightly shining. Spire rather short, conic, about two-thirds 

 the height of the aperture ; outlines slightly convex. Protoconch 

 small, of 1 smooth globular whorl, semitransparent. Whorls 4, rather 

 flattened, the last large, somewhat ventricose ; base rounded. Suture 

 deep. Aperture ovate, vertical, angled above. Outer lip thin and 

 straight, lightly convex. Basal lip narrowly rounded. Columella 

 oblique, rounded, inconspicuously twisted. Inner lip callously and 

 broadly reflexed over the body-whorl, and completely covering the 

 umbilical area. 



Diameter, 6-75 mm. ; height, 12 mm. ; aperture, 5 mm. by 8-5 mm. 

 (type). 



Animal unknown. 



Type in the Canterbury Museum, Christchurch. 



Hob. Wellington. 



3. 



Lymnoea pusilla, Hutton, 1885 (em.). Plate 24, fig. 12. 



Limncea pucilla, Hutton, T.N.Z.I., xvii, 1884 (1885), 56, pi. 12, f. 5. Limnvea 

 pusilla. Hutt. : Hedley and Suter, P.L.S. N.S.W. (2), vii, 625 ; Suter, 

 J. de Conch., xli, 1893 (1894), 230. 



Shell very small, oblong, glossy, translucent, thin and fragile. 

 Sculpture, consisting of very fine growth-lines. Colour light-horny. 



