PETTERD : NEW TASMANIAN SHELLS. 1 45 



36. dementia Tasmanica n. sp. Shell very thin, trans- 

 versely ovate, inequilateral, equivalve, yellowish-brown, 

 sub-pellucid ; outer surface with irregular concentric 

 lines of growth crossed by fine radiating wavy strise ; 

 interior margin not dentate, pinkish white. Long. 

 II mill., lat. 15 mill. 



Habitat, Dredged off Long Bay and Brown's 

 River in about 7 fathoms. 



A very fragile bivalve, but rarely obtained. 



Myochama Woods! i n. sp. Shell thin, very irregular, 

 somewhat foliaceous, yellowish white ; umbones very 

 distinct, trigonal, concentrically ridged, ridges raised 

 and rounded, interspaces reticulate ; interior shining, 

 nacreous. Long. 10 mill., lat. 10 mill. 



Habitat, D'Entrecastreaux Channel, dredged in 

 about 7 fathoms, parasitic on Peden laiicostatus and 

 F. asperrimus. 



Fully developed examples are but rarely obtained. 

 I have only seen it attached to the shells mentioned. 



Valvata piscinalis monst. sinistrorsum in Derby- 

 shire. — I am indebted to Mr. Edgar Pickard, of Mansfield, 

 for the loan of a very interesting collection of our land and 

 freshwater shells, mainly illustrating the fauna of Derbyshire. 

 Amongst the shells are several more or less scalariform speci- 

 mens of Valvata piscinalis collected at Cresswell Crags in 

 Derbyshire. Two of these are sinistral, one appears to be 

 adult, the s econd is only half-grown. The only other speci- 

 men ori record that I know of, is that noticed by Dr. Jeffreys, 

 as found by Mr. Grove at Sunbury. — J. W. Taylor, Dec, 

 1883. 



