LEDA. 155 



Habitat : Mud and sand, in 20-86 fathoms, on the 

 Antrim coast, Skye, Hebrides, and Shetland. It is 

 very local in a recent state, but widely diffused in 

 glacial beds, and occurs also in the Coralline Crag. 

 Many conchologists have noticed it as an arctic and 

 Scandinavian species ; Danielssen and Asbjornsen say 

 it is found on the Norwegian coast at depths varying 

 from 10 to 140 fathoms, and Malm on the coast of 

 Sweden in 30-53 fathoms. The only southern habitat 

 that I am aware of is Naples, where Scacchi is said 

 (according to Philippi) to have taken it. It is a tertiary 

 fossil in Siberia and Sicily. 



Some specimens are shorter and more gibbous than 

 others. Owing to the semitransparency of the shell, 

 the teeth are distinctly visible outside the hinge-line. 



Philippi named this species Nucula tenuis, before he 

 was aware that Goldfuss had described it, or that Mon- 

 tagu had already used that name for another species. 

 Mr. James Smith called this species Nucula gibbosa, 

 and Moller N. lenticula. The Yoldia abyssicola of Torell 

 and Sars is probably a variety of the present species. 

 The Y, lucida of Loven seems different. 



B. Shell triangularly oblong, transversely ribbed, with two 

 ridges extending obliquely from the beak in each valve 

 to the posterior extremity, which is truncate and some- 

 what open : teeth set in a herring-bone fashion. 



2. L. minu'ta*, Muller. 



Area minuta, Mull. Prodr. Zool. Dan. p. 247, no. 2985. L. caudata, 

 F. & H. ii. p. 226, pi. xlvii. f. 11-13, and (animal) pi. P. f. 2. 



Body oblong and pear-shaped, greyish -white: mantle fringed 

 or denticulated at its posterior side by a row of five very short 



* Small. 



