100 HELIX-CHAROPA. 



Forty mile Bush, North Island, New Zealand. 

 P. colensoi SUT., Trans. N. Z. Inst. xxii, p. 225, t. 14, f. la, b ; I. 

 c. xxiv, p. 293, t. 21, f. 26, 27 (jaw and dentition.) 



Named in honor of the Rev. William Colenso, F. R S., the dis- 

 coverer of the Unio ivaikarense. This species is near Pat. infecta 

 Reeve, but differs sufficiently from it to justify the creation of a new 

 species ; the direction of the ribs on the surface is different ; there 

 are only 5 whorls, more rapidly increasing, and the last consider- 

 ably more developed ; the peristome has no callosity ; the umbilicus 

 is a little narrower ; the diameter is greater, the color darker, the 

 ribs coarser and rather more distant. (Sut.) 



P. VARIECOSTATA Suter. PL 19, figs. 19, 20, 21. 



Shell discoidal, small, white, with large yellow streaks at regular 

 distances, faintly shining, fragile, transparent, with close, fine ribs, 

 directed forwards on the upper surface and going straight down on 

 the side ; there is alternately one much higher than the next ; 

 interstices striated with growth lines and reticulated with spirals. 

 Ribs about 38 in the tenth of an inch (15 per mm.). Spire flat, 

 only the first whorls a little elevated. Whorls 5, slowly and regu- 

 larly increasing, swollen, the last not descending. Suture very 

 deep. Aperture slightly oblique, rotundly lunar, but little excava- 

 ted by the penultimate whorl. Peristome straight, acute, somewhat 

 tapering, columellar margin nearly vertically descending, upper 

 and lower margins strongly arcuated. Umbilicus broad, perspective, 

 about one-third of the diameter. Alt. 1, diam. 1-8 mill. (Suter.) 



Mauriceville, North 1., New Zealand. 



P. variecostata SUT., Tr. N. Z. Inst. xxii, p. 225, t. 14, f. 8. 



P. RARICOSTATA Suter. PL 19, figs. 22, 23, 24. 



Shell small, depressed, subdiscoidal, color dark olive, not shining, 

 fragile, with distant, stout, dark brown ribs, bent backwards on the 

 upper surface and slightly undulating on the side. Ribs about 12 

 in the tenth of an inch (5 per mill.). Spire slightly elevated. 

 Apex white, bare of epidermis. Whorls 5, slowly increasing, 

 rounded, the last not descending. Suture not deep. Aperture 

 oblique, nearly circular, but very little excavated by the penulti- 

 mate whorl. Margins convergent. Columellar margin slightly 

 reflected, descending vertically. Lower margin strongly arcuated. 



