346 DONACIDiE. 



SPURIOUS. 



Under the name of Mactra deaurata, Dr. Turton has intro- 

 duced into our Fauna a species of the genus Mesodesma, stating 

 that it was dredged up in the offing of Exmouth. One of our 

 most assiduous and scientific collectors, Mr. Clark of Bath, 

 whose researches in that neighbourhood extended over a period of 

 twenty years, during that long space of time never once procured 

 a single specimen, a strong, although negative, proof of the indi- 

 vidual shell described by the doctor being of foreign importation, 

 and not of native origin. The species is an inhabitant of the 

 Gulf of St. Lawrence, Newfoundland, and does not range to the 

 European seas. Inquiries instituted on the Devonshire coast 

 have enabled us to solve the mystery of the discovery of this and 

 other transatlantic shells in spots so utterly at variance with their 

 known habitats. We find that during many years several vessels 

 from those parts were engaged in prosecuting the Newfoundland 

 fisheries ; so that the accidental appearance of a few specimens of 

 northern shells may readily be accounted for, as they frequently 

 are mingled with the ballast of ships. A comparison of the ori- 

 ginal type with its delineation in the Conchylia Dithyra, compels 

 the remark, that it is represented as more narrow and elongated 

 than nature has shaped it, and enables us to declare its perfect 

 identity with examples of the Mesodesma Jauresii, received by us 

 from North America. 



M. DEAURATA, Turtoil. 



Mactra deaurata, Turt. Dithyra, Brit. p. 71, pi. !>, f. fi. — Flem. Brit. Anim. 

 p. 427. 

 „ denticulata. Index Test. Suppl. pi. 1, Mactra, f. 9. 

 Mesodesma denticulata. Gray, Cuv. Anim. King. (ed. Grif.) pi. 22, f. 2. 



inspection of the typical example of Tcllina pellucida, which, crushed as it unfor- 

 tunately then was through transmission by post, still remained sufficiently united 

 to enable us to state with certainty that it is not an adult shell, (it was not unlike 

 the fry oi Scrobiculana piperata,) and that the engraving of it (111. Conch. G. B. 

 pi. 40, f. 22) scarcely presents any 'resemblance to the species, the dorsal edge 

 not being incurved, and the hinder termination not being roimdod (as delineated) 

 but subangular. 



