234 ANATINIDiE. 



The Thracki dlstorta is sometimes mistaken for a borer, 

 on account of its habit of inserting itself into crevices of 

 rock, where it assumes not unfrequently those eccentric 

 variations of form which have given rise to its specific 

 appellation. 



Though on the whole to be regarded as a scarce shell, 

 it is very generally distributed. We have dredged it in 

 about ten fathoms water at Torquay, alive and embedded 

 in masses of limestone (S. H.) It has been taken at Ex- 

 mouth (Clark) and Falmouth, where the variety truncata 

 occurs (Jeffreys). We have taken dead valves from the 

 rocks upon the shore at Weymouth, nearly opposite the old 

 castle (S. H.), and have dredged it at Guernsey (S. H.), 

 lodged in a very thick oyster-shell. Lieut. Thomas has 

 dredged it alive on a stony bottom in twenty-seven fathoms 

 water off the coast of Northumberland. On the Welsh 

 coast Mr. Jeffreys has taken it at Swansea and the adja- 

 cent bays, and Mr. Lyons at Tenby. We have dredged 

 it off the Isle of Man (E. F.) In Ireland it was found on 

 the north coast by Mr. W. Thompson, and at Youghal 

 by Mr. Ball. In Scotland Mr. Jeffreys takes it at Tarbert 

 Island, and Mr. M'Andrew in the Hebrides. The Rev. 

 G. Laing communicates it from the Orkneys, and we have 

 found it in the Frith of Forth (E. F.) Laskey long ago 

 recorded it from Dunbar. 



It is not known fossil ; as a foreign shell, it is record- 

 ed from the north-west coasts of Norway by Loven, and 

 the Thracia brevls of Deshayes (Moll. Alger., pi. 81) from 

 the coast of Algiers does not seem materially to differ from 

 it. 



