PETTERD : NEW TASMANIAN SHELLS. 1 37 



almost conceal them ; apical whorl smooth ; aperture 

 darker tint, ovate, outer lip thin ; canal rather short. 

 Long. 6 mill, lat. 3}^ mill. 



Habitat, Tamar Heads. 



Of this very distinct fofm I have only seen four 

 examples, we may therefore conclude that it is 

 somewhat rare. In sculpture it is so very unlike any 

 any other species that it can be easily identified. It 

 may possibly attain a larger size than the measurements 

 given above, but they are taken from the largest 

 specimens in my collection. 



Rissoa lineata n. sp. Shell small, conical, turreted, 

 whitish with several spiral chestnut-brown lines; whorls 

 4}^, longitudinally ribbed, base with several transverse 

 raised lines ; aperture ovate. Long, i^ mill, lat. 

 I mill. 



Habitat, North Coast, on the underside of exposed 

 rocks at low-water. 



Rissoa dubius n. sp. Shell ovate, dark bluish-brown, 

 smooth, shining, moderately thick; whorls 4j4, spire 

 short; aperture large, somewhat expanded, labrum 

 white. Long. 2 mill., lat. i mill. 



Habitat, Tamar Heads ; collected on the rocks 

 at low water. 



Rissoa bicolor n. sp. Shell ovately conical, smooth, 

 shining, rich brown colour, with a broad sordidly 

 white band next the suture ; whorls 6, without sculp- 

 ture, suture moderately impressed ; aperture small, 

 ovate, entire, thickened. Long 3}^ mill., lat. 2 mill. 



Habitat, North coast. 



A very abundant form at low water, with the two 

 preceding. 



