24 



determined to a great extent by the original aperture of apical 

 tier ; inner lip with slightly raised rim continuous, simple. 

 In the young state the shell is simple, and resembles the 

 common Ancylus in the same neighbourhood. Long. 2| — 3^ 

 lat. 1| — IJ, alt. J — |. Animal pale yellowish, with broad 

 roundish muzzle, two short subulate tentacles ; eyes sessile 

 behind tentaculae ; mouth with dark_ serrated horny jaws, 

 tongue linear, oblong, teeth numerous, 96 rows ^| — 1 — \% ; 

 laterals equal, hooked, and inclined away from saddle-shaped 

 medial, as in Avicula (see p. 303, Woodimrd). Habitat, on 

 dead leaves in a pool, 1st Basin, Launceston ; isolated from 

 the South Est. 



This is a most interesting genus, hitherto confined to 

 America and Cuba. The Tasmanian species differs from 

 the Cuban one, G. ancyliformis, in being smaller, and, 

 relatively to length, broader ; the former being three times 

 as long as it is broad, the latter scarcely twice as long as- 

 it is broad. It also differs in the position and shape of 

 inner aj^erture, the Tasmanian species being more central 

 and more rounded anteriorly. An examination, under the 

 microscopic, of the animal proves that it is closely allied to 

 Ancylus. The teeth in the latter are simply fewer and larger. 

 Both Gundlacliia Petterdi and Ancylus Woodsii feed on diato- 

 macea. I found large numbers of the frustules of various 

 species in their stomachs. I have dedicated the species to 

 Mr. Petterd, who has materially enriched our Tasmanian 

 collections. 



Amnicola. Gould and Haldemann, 1839. 



Shell ovate, conical turbinated, covered with an ej^idermis, 

 not perforated ; sj)ire acute ; whorls few, rounded ; aperture 

 large, orbicular, and straitened backward ; peristome conti- 

 nuous, outer margin thin, simple ; operculum horny, spiral 

 or paucispiral. 



Amnicola lauxcestoxensis. n. s. 



Shell solid, small, globosely conical, with a short, somewhat 

 acute, spire ; epidermis dark, granular ; whorls 4|, convex, 

 rapidly decreasing ; body whorl much inflated, forming two- 

 thirds of the whole length of shell ; suture deeply im2)ressed, 

 aperture widely ovate, peristome continuous, outer lip slightly 

 reflexed, inner lij) obliquely reflexed against body whorl, 

 causing a faint apjjroach to an umbilicus ; throat bluish 

 white, shelly ; operculum horny, paucispiral. Diam.— Max. 

 5 mil., min. 3 mil. Habitat — Still water, though in commu- 

 nication with the South Esk ; in caverns, cataract, Launceston. 



I have somewhat doubtfully referred this sj^ecies to the 



