the West Coast of Davis's Strait. 335 



glossy except on the posterior portion, where the brightness is 

 considerably subdned. Old specimens are almost entirely black ; 

 the young are varied with rich brown, black and pale yellowish 

 green, or are wholly of the latter colour. 



There can be no doubt that the variety ft. substriata, which 

 Mr. Gray thought might prove distinct, belongs to this species. 



I think it probable that the Mytilus discors of Fabricius in- 

 cludes this species, though under that name he appears to have 

 described more than one kind ; for he states that whilst the young 

 are striated at both ends, the old are smooth on the front portion. 

 This is not the case with the suite brought by Messrs. Warham 

 and Harrison ; the young, and some of them are very small, are 

 quite smooth on the posterior compartment. 



Tellina calcarea, Gmelin. 

 Tellina calcarea, Gmelin, p. 3236. no. 38. 

 Tellina proxima, Brown, Wern. Mem. vol. viii. t. 1. f. 21 ; Sow- 

 erby, App. Beechey's Voy. p. 154. t. 44. f. 4. 

 This did not occur abundantly ; only six or seven specimens 

 were dredged. The epidermis occasionally covers almost the 

 whole shell, and is generally more entire than in the specimens 

 from which Mr. Sowerby described. 



Astarte semisulcata, Leach sp. 



Crassina semisulcata, Leach, App. Ross's 1st Voy. 8vo ed. 

 Astarte lactea, Brod. and Sow., Zool. Journ. vol. iv. p. 366 ; 



Sowerby, Zool. Beechey's Voy. p. 152. pi. 44. f. 12. 

 Crassina corrugata, Brown, Conch, of Great Brit. 2nd ed. p. 96. 



pi. 40. f.24. 

 Crassina Withami, Smith, Wern. Mem. vol. viii. pi. 1. f.24, 25. 



This is rather a variable species, but may always be distin- 

 guished from A. boreale, with which some conchologists have 

 confounded it. It is sometimes nearly smooth, or only obso- 

 letely sulcated at the umbones ; in this state it is Brown's Cras- 

 sina corrugata ; others are sulcated at least half-way down, and 

 the young, as might be expected, are furrowed over the whole 

 surface. Individuals occur nearly black, not much compressed, 

 and of a roundish oval, but by far the greater number are of a 

 yellowish brown colour, with the valves very flat and much pro- 

 duced transversely. 



This species is frequently distorted, and is generally much 

 eroded at the beaks. It is found fossil at Bridlington ; I have 

 seen very characteristic specimens from thence in the collection 

 of Mr. Loftus of Newcastle, who received them from Mr. Bean 

 under his manuscript name of Astarte lata. The description of 

 Crassina Withami of Smith agrees very accurately with the smooth 

 varieties of A. semisulcata, and the figures in the 'Wernerian 

 Memoirs • put it beyond a doubt ; the straight ventral margin and 



ii 



