Endodonta.} GASTROPODA. 729 



33. Endodonta biconcava, Pfeiffer, 1853. Plate 28, figs. 20, a, b. 



Helix biconcava, Pfr., M.H. Viv., iii, 1853, 109 ; P.Z.S., 1852 (1854), 149 ; 

 Reeve, Conch. Icon., vii, pi. 132, f. 810 ; Conch. Cab. (2), i, 458, pi. 155, 

 f. 43-47 ; Hector, Cat. Land Moll. N.Z., 13. Diplomphalus biconcava, 

 Pfr., Nomencl. Hel. Viv., 25. Patula biconcava, Pfr. : Hutton, M.N.Z.M., 

 11 ; T.N.Z.I., xvi, 193. Elcea biconcava, Pfr. : Tryon, Man. Conch. 

 (2), i, 130, pi. 24, f. 75. Charopa biconcava, Pfr. : Hedley and Suter, 

 P.L.S. N.S.W. (2), vii, 658. Endodonta (Charopa} biconcava, Pfr. : 

 Suter, J. de Conch., xli, 266. 



Shell small, discoidal with, concave spire, broadly umbilicated, 

 closely arcuately ribbed, opaque, horny with light-brown streaks, a 

 distinct sinus at the suture. Sculpture consisting of oblique radial 

 riblets, fine and close together on the protoconch, about 10 per milli- 

 metre at the periphery ; they are distinctly protractive above, arcuate 

 on reaching tlie periphery, thence flexuous and gently directed back- 

 wards ; interstices with a few growth-lines, no spirals. Colour horny- 

 yellowish, rufously streaked. Spire concave. Protoconch of 1^ con- 

 vex turns. Whorls 5, the first four slowly increasing, distinctly angled 

 above, periphery and base rounded. Suture well impressed. Aperture 

 subvertical, higher than broad, lunate. Peristome simple, sharp, re- 

 tracting at the suture and forming a conspicuous sinus. Columella 

 short, arcuate. Inner Up slightly expanded ; parietal wall with a 

 broad shining whitish glaze. Umbilicus broad, perspective. 



Diameter Maj., 5 mm. ; min., 4-3 mm. : height, 2 mm. 



Dentition. Suter, T.N.Z.I., xxiv, 295, pi. 22, f. 30, 31. 



Jaw slightly arcuate, membranous, vertically striated. 



Radula having the formula 120 x 14 + 5 + 1 + 5 + 14. Central and 

 lateral teeth tricuspid, with long mesodonts. Marginals tridentate, 

 the mesodont longest, teeth mostly curved. 



Type in the British Museum. 



Hob. North Island : Thames (Adams) ; Heretaunga (Brooks) ; 

 Forty-mile Bush ; Wellington (H. S.). 



Forma minor, Suter. 



Distinguished from the species by its smaller size only ; the number 

 of riblets is the same ; whorls also 5. 



Diameter Maj., 4 mm. ; min., 3-5 mm. : height, 1-75 mm. 



Type in my collection. 



Hob. Dunedin, type (H. S.) ; Fortrose (Miss Rich). 



34. Endodonta Huttoni, Suter, 1890. Plate 29, figs. 1, a, b. 



Diplomphalus Huttoni, Sut., T.N.Z.L, xxii, 1889 (1890), 226, pi. 15, f. 11, 

 a, b.. Patula Huttoni, Sut., T.N.Z.L, xxiv, 273. P. (Charopa) Huttoni, 

 Sut. : Pilsbry, Man. Conch. (2), viii, 104, pi. 19, f. 43-45. Charopa 

 Huttoni, Sut. : Hedley and Suter, P.L.S. N.S.W. (2), vii, 659. Endo- 

 donta (Charopa) Huttoni, Sut., J. de Conch., xli, 270. 



Shell small, discoidal with sunken spire, umbilicated, radially 

 delicately costate, thin and fragile, translucent, light horn-colour. 



