Leptolhi/ra.\ GASTROPODA. 165 



Outer and basal lip acute, thickened inside. Columella arcuate, some- 

 what produced and expanded at the base. Inner Up spreading as a 

 thick callus over the parietal wall. Umbilicus small and deep. Oper- 

 culum circular, somewhat calcareous, of 6 or 7 narrow whorls ; the 

 nucleus central. 



Diameter, 3-2 mm. ; height, 2-5 mm. 



Dentition unknown. 



Type in the Dominion Museum, Wellington. 



Hab. Whangaroa Harbour (C. Traill) ; Snares, in 50 fathoms 

 (Captain Bollons). 



2. Leptothyra fluctuata, Hutton, 1883. Plate 34, fig. 11. 



Cydostrenm fluctiicita, Hutt,, N.Z.J.S., i, 1883, 477 ; T.N.Z.I., xvi, 215. 

 Leptothyra fluctuata, Hutt., Man. Couch. (1), x, 259, pi. 64, f. 47, 48; 

 Murdoch, T.N.Z.I., xxxvij, 222, pi. 7, f. 10. 



Shell small, rather solid, spirally striated, umbilicate, not iridescent. 

 Sculpture consisting of close spiral cinguli. 25 to 35 on the last whorl ; 

 the umbilical area smooth or cut up with strong irregular growth- 

 periods. Colour yellowish-white, pale brownish, or pink, with irregular 

 waved longitudinal bands of brown extending across the base, but not 

 reaching the umbilicus. Spire depressed, outlines convex. Protoconch 

 of 1 smooth white whorl. Whorls 3 to 4, rounded, the last large ; base 

 convex. Suture slightly impressed. Aperture subrotund, white within. 

 Outer and basal lip convex, acute, thickened within. Columella 

 vertical, concave, united by a thick callus with the basal lip. Inner 

 lip forming a thin callosity upon the parietal wall. Umbilicus narrow, 

 deep. Operculum, inside as usual in the genus, showing about 6 closely 

 coiled whorls ; outside subvitreous and translucent, nearly smooth, 

 calcareous, slightly concave in the centre. 



Diameter, 3 mm. ; height, 2-25 mm. 



Dentition unknown. 



Type in the Canterbury Museum, Christchurch. 



Hob. Foveaux Strait (type) ; Port Pegasus, Stewart Island, in 

 18 fathoms (Captain Bollons) ; Hauraki Gulf, in 20 fathoms (R. H. 

 Shakespear) ; Whangaroa Harbour (C. Traill) ; Bounty and Snares 

 Islands, in 50 fathoms (Captain Bollons). 



Fossil in the Pliocene. 



Var. immaculata, Suter, 1908. 



Leptothyra fluctuata, var. immaculata, Suter, P. Mai. S., viii, 27. 



Distinguished from the species in being larger, having more 

 numerous closer spiral cinguli, and no colour-markings at all. My 

 specimens (empty shells) are white. 



Diameter, 4 mm. ; height, 2-5 mm. 



Type in my collection. 



Hob. Snares, in 50 fathoms (Captain Bollons). 



