Allo(ii*c.>i..i.\ GASTROPODA. 647 



14. Allodiscus Urquharti, Suter, 1894. Plate 25, fig. 16, a, b. 



Allodiscus Urquharti, Sut., P.L.S. N.S.W. (2), viii, 489, pi. 22, f. 4, a~d. 

 Flammulina (Allodiscus) Urquharti, Sut., J. de Conch., xli, 253 ; T.N.Z.I., 

 xxxiv, 205. 



Shell very minute, globosely depressed, umbilicated, silky, thin 

 and fragile, transparent. Sculpture : Protoconch microscopically spir- 

 ally striate ; the succeeding whorls with extremely fine and close- 

 set radiate riblets. which are slightly protractive and reach to the 

 umbilicus ; they number about 40 per millimetre ; the interstices are 

 microscopically reticulated. Colour horny, without any markings. 

 Spire short, convex, about half the height of the aperture. Proto- 

 conch of 1| convex whorls. Whorls 3^ to 4, narrow, slowly and regu- 

 larly increasing, convex, the last not descending, periphery and base 

 rounded. Suture deep. Aperture subvertical, rotundly lunate, much 

 excavated by the penultimate whorl. Peristome simple, straight, 

 acute, margins convergent. Columella very short. Inner lip regu- 

 larly arched, not reflexed. Umbilicus narrow, about one-sixth of the 

 greatest diameter, deep and open. 



Diameter Maj., 1-5 mm. ; min., 1-25 mm. : height, 1 mm. 



Jaw arcuate, consisting of about 14 thin plaits, indenting both 

 margins. The central plaits are broader than those on the sides, and 

 are separated by a narrow interstice. 



Radula with the formula 18 + 1 -I- 18 ; 3 to 4 laterals. Central 

 tooth with small rounded reflection and a sharp mesodont. Laterals 

 bicuspid, with short cutting-points. Marginals with 3 to 4 cutting- 

 points, the inner second point is longest ; last marginal with 3 cutting- 

 points. 



Type in my collection. 



Hob. Mount Pirongia, type (T. Urquhart) : Hunua Range (Major 

 Broun) ; Little Barrier Island (Adams). 



Remarks. This is the minutest, widest umbilicated, and one of the 

 closest ribbed species of the genus. 



15. Allodiscus venulatus, Pfeiffer, 1857. Plate 25, fig. 17, a, b. 



Helix venulata, Pfeiffer, P.Z.S., 1857, 108 ; M.H. Viv., iv, 163 ; Hector, 

 Cat. Land Moll. N.Z., 18. Nanina (Microcystis) venulata, Pfr., Nomencl. 

 Hel. Viv., 36. Charopa (Psyra) venulata, Pfr. : Tyron, Man. Conch. 

 (2), ii, 211. Patula (Flammulina) venulata, Prf . : Hutton, M.N.Z.M., 

 10. Psyra venulata, Pfr. : Hutton, T.N.Z.I., xvi, 201. Allodiscus 

 venulatus, Pfr. : Hedley and Suter, P.L.S. N.S.W. (2), vii, 638. Flam- 

 mulina (Allodiscus) venulata, Pfr., Man. Conch. (2), ix, 15; Suter, 

 J. de Conch., xli, 251. 



Shell depressed, imperforate, thin, closely costate, diaphanous. 

 Sculpture : Protoconch microscopically spirally lirate ; the following 

 whorls with sharp sinuous radiate riblets, 5 to 6 on the periphery, 

 10 to 11 per millimetre near the suture ; interstices with fine growth- 

 lines and not very prominent microscopic spiral striae. Colour cor- 

 neous, variegated with light-reddish-brown markings. Epidermis thin, 



