TASMANIAN LAND SHELLS. 37 



56. — Helix ( ) Bassi — Brazier. 



Pro. Zool. Soc, 1871. 



H. ainmonitoides — Brazier. 



Pro. Zool. Soc, p. 661, 1870. 

 Legrand, Col. for Mon., sp. 50. 



H. vigens — Cox. 



Legrand, Col for Mon., sp. 40, pi. ii., fig. 5. 



Shell umbilicated, flatly discoid, not shining, finely and prominently, 

 irregularly ribbed, the interstices with very fine striae, white beneath a 

 thin brown epidermis ; spire flat ; suture slightly impressed ; whorls 3|-, 

 very regularly increasing, last rounded above and below ; base convex, 

 with strise the same as on upper surface ; umbilicus large, with the 

 bottom flat, not very deep ; aperture oblique, roundly-lunate ; peristome 

 simple, the thin epidermis covering it ; margins approximating. 



Diameter, greatest 0*11, least 0*10 ; height, 0*05 of an inch. 



Habitat. — Mount Nelson ; Domain, Hobart Town (a single 

 specimen). 



Although resembling many of our minute shells, a close examina- 

 tion proves it to be distinct from all ; it may be known by its flat form, 

 white colour, thin epidermis, coarse striae, and very shallow umbilicus. 

 It is of exceptional occurrence, and, so far as I am aware, confined to 

 the southern portion of the island. 



57. — Helix ( ) Lottah. N. Sp. 



Shell openly umbilicated, depressed, discoid, translucent, thin, 

 white, scarcely shining, regularly rather coarsely ribbed throughout, 

 interstices with extremely fine striae ; spire flat ; suture moderately 

 impressed ; whorls 4J, slightly convex, apical (2 J) quite smooth, last 

 rounded, not descending in front, below with striae as above running 

 into the somewhat shallow, open umbilicus, which is flattened at the 

 bottom ; aperture lunate ; peristome simple, thin. 



Diameter, greatest 2J, least 2 ; height, 1 mil. 



Habitat. — Cataract Hill, near Launceston, on the under surface of 

 large boulders. 



A pure white species allied to H. Roblini (mihi)^ but that species is 

 finely striated throughout, and its umbilicu3 is not nearly so open. To 

 H. Bassi (Brazier) it is so closely related that it may possibly be but a 

 variety, but it is much smaller, has a much less shallow umbilicus, and 

 the riblets are coarser than in its larger congener. I therefore pro- 

 visionally describe it. All three are of the same habit, found on the 

 Tinder surface of boulders, generally in rather dry situations, and all are 

 extremely rare. 



