198 MYTILIDjE. 



depth we have found it in the Irish Sea, off Anglesea, in 

 the line of strong currents, enveloped in nests formed of 

 fragments of Flustra foliacea and masses of sand aggluti- 

 nated together and combined by byssal threads. Mr. 

 Alder has observed a slender nearly smooth variety among 

 the rocks at Staifa. It ranges throughout the European 

 seas, and probably also to the shores of Boreal America. 



C. MARMOHATA, Forbes. 



Tumid, oblique, usually marbled with coloured markings, 

 smooth in the middle, rayed with impressed lines at both ex- 

 tremities ; beaks quite terminal. 



Plate XLV, fig. 4. 



Mytiius discors (not of Linn, nor Fabr.), Da Costa, Brit. Conch, p. 221, pi. 17, 

 f. 1. — Pulteney, Hutchins, Hist. Dorset, p. 38. — Donov. 

 Brit. Shells, vol. i. pi. 25, f. 1. — Mont. Test. Brit. p. 167.— 

 Maton and Rack. Linn. Trans, vol. viii. p. 111. (not var.) 

 pi. 3, f. 8. — Laskey, Mem. Wern. Soc. vol. i. p. 393. — 

 Rackett, Dorset Catalog, p. 40, pi. 2, f. 1. — Turt. Conch. 

 Diction, p. 112.— Poli, Test. Sicil. vol. ii. p. 211, pi. 32, f. 15. 

 — Diluv. Recent Shells, vol. i. p. 319. Index Testaceolog. 

 pi. 12, f. 39.— Mawe, Conchology, pi. 13, f. 5. 

 Modiola „ (not of Lamarck), Turton, Dithyra Brit. p. 201, pi. 15, f. 4, 5. — 

 Fleming, Brit. Anim. p. 413. — Macgilliv. Moll. Aberd- 

 p. 239.— Brit. Marine Conch, p. 108. 

 Mytiius discrepans, Deshayes, Encyclop. Method. Vers. vol. ii. p. 567. 

 Modiola marmorata, Forbes, Malacol. Monens. p. 44. — Brown, 111. Conch. 

 G. B. p. 78, pi. 27, f. 10. 

 „ discrepans, Philippi, Moll. Sicil. vol. i. p. 70, and vol. ii. p. 50, pi. 15, 



f. 11. 

 „ tumida, Hanl. Recent Shells, vol. i. p. 241, pi. 12, f. 39. 

 „ Poliana, Philippi, Zeitschr. Malacol. 1844, p. 101 (from type). 



Few shells have been the subject of more discussion 

 than the Mytiius discors of Linneeus, which epithet, usually 

 bestowed by foreign writers upon the large Australian 

 species (impacta), has, till of late years, been almost uni- 



