96 MOLLUSCA FROM THE CRAG. 



The living animal has recently been obtained by Mr. M'Andrew, from the depth 

 of nearly 50 fathoms, on a muddy bottom, in the Sound of Skye ; and it is quoted by 

 Loven as an existing species on the Coast of Finmark, while Moller gives it from the 

 Greenland Seas. 



8. LEDA THRACI^FORMIS, Storer. Tab. X, fig. 15. 



NUCULA THRACLEFORMIS. Stor. Bost. Journ. Nat. Hist., vol. ii, p. 122, 1838. 



Gould. Invert. Massach., p. 97. fig. 66, 1841. 

 Dekay. Nat. Hist. New York (Zoology), p. 178, pi. 12, fig. 217, 

 a b, 1843. 



Spec. Char. " Testa ovato-o&longd, transversd, nigrd, crassd ; antice rotundatd, postice 

 truncata et compressd, umbonibns prominentibus ; cardinefoved magnd" (Storer.) 



" Shell ovato-oblong, transverse, black, and thick ; anterior side rounded, posterior 

 truncated and compressed, beaks prominent, with a large ligamental pit." 



The specimen figured, was obtained by R. M'Andrew, Esq., a gentleman to 

 whom science is so largely indebted for a more correct knowledge of our native 

 Marine Fauna. This novelty is the result of one of his very recent explorations in 

 the Sound of Skye, and was dredged, he tells me, at the depth of about 50 fathoms, 

 and found in association with Leda truncata, Pecten Islandica, &c., species supposed to 

 have become extinct in our own Seas, though still existing in some other regions of 

 the Northern Hemisphere : the specimen (although but a fragment, is a considerable 

 portion of the shell), was consigned to Professor E, Forbes, who is also of opinion 

 that it is identical with Leda Thraciteformis, and I am much indebted to those two 

 gentlemen for the privilege of being the first to make it known as having once been an 

 inhabitant of our own Seas ; and although it be another, to which as a describer of 

 the Crag species I may not strictly have a claim, it belongs at least to the bygone 

 times, and comes into the province of the Palaeontologist. 



What remains of the specimen seems to justify its being considered as belonging 

 to the species to which it is here assigned, although the most characteristic portion of 

 the shell is destroyed ; I have, therefore, copied the specific character from the 

 original describer : it differs from L. truncata in being somewhat thinner and more 

 compressed, but there is scarcely enough of the shell remaining to show satisfactorily 

 the peculiar ridge on the posterior side sloping from the umbo to the extremity of 

 the ventral margin : it is ornamented with concentric striae, like L. truncata, and they 

 are slightly wavy in their direction. 



The specimens of this species hitherto recorded as having been found in the recent 

 state were from the stomachs of the Cod and Sand-dab, and these fishes were taken 

 at the depth of 30 fathoms and upwards. 



The outline tracing is copied from the figure of the recent shell in Dr. Gould's 

 1 Invertebrata of Massachusets.' 



