BIVALVIA. 229 



TELLINA OVATA. J. Sow. Min. Conch., t. 161, fig. 2, 1817. 



Phil. En. Moll. Sic., vol. i, p. 30 : vol. ii, p. 23. 

 Nyst. Coq. Foss. de Belg., p. 108, pi. 5, fig. 3, a, b, 1844. 



OVALIS. Woodw. Geol. of Norf., p. 43, pi. 2, fig. 11, 1832. 



SABTJLOSA. Spengler. Sec. LovSn. 



CALCAREA. Wcthlenb. Sec.Lyell. Geol. Trans., vol. vi, 2d series, p. 137, pi. 16, 



figs. 911, 1839. 



Holler. Ind. Moll. Groenl., p. 20, 1842. 



PROXIMA. Smith, Mem. Wern. Soc., vol. viii, p. 105, pi. 1, fig. 21, 1838. 

 Sow. Append. Beechey's Voy., p. 154, t. 44, fig. 4, 1839. 

 Forb. and Hani. Hist. Brit. Moll., vol. i, p. 307, pi. 21, fig. 1, 1848. 

 EDENTTJLA. ? Brod. and Sow. Zool. Journ., vol. iv, p. 363, 1829. 



? Gray. App. Beech. Voy. Zool., p. 154, t. 41, fig. 5 ; and t. 44, fig. 7, 

 1839. 



SORDIDA. Couthony. Bost. Journ. Nat. Hist., vol. ii, p. 59, pi. iii, fig. 11, 1839. 



TRIANGULARIS. Lyell. Phil. Trans., 1835, p. 36, fide Lovtn. 



TENERA. Gray. List Brit. Moll., p. 42, 1851. 

 SANGUINOLARIA SORDIDA. Gould. Invert. Massach., p. 67, 1841. 

 MACOMA TENERA. Leach. Ann. of Phil., vol. xiv, p. 204, 1819. 



Spec. Char. Testa ovatd, transversd, intsquilaterali ; anticelongiore rotundatd ; postice 

 sub-angulatd ; dentibus utrinqne binis, lateralibus nullis. 



Shell ovate, transverse, inequilateral ; anterior side the longer and rounded ; 

 posterior obtusely angulate, with two teeth in each valve; lateral teeth none. 



Length, If inch. Height, \\ inch. 



Locality. Red Crag, Sutton. 



Mam. Crag, Bramerton, Chillesford. 

 Clyde Beds, Uddevalla, Russia, Canada. 



Recent, Finmark, N. E. Coast of America, Britain, 

 Behring's Straits (G. B. Sowerby). 



I have never seen the present species from the Older or Coralline, and only rarely 

 from the Red Crag, and never at Walton-on-the-Naze. In the Mammaliferous Crag 

 Period the two species appear to be more equally distributed, although the oblique 

 form is there giving way to its more transverse successor, while this latter species 

 only, remains at the present day, and seems to be restricted to the colder regions of 

 the Northern Hemisphere. In this, as in the preceding species, there is a considerable 

 difference in the form and depth of the siphonal scar in the two valves, and the 

 posterior side of this one is much more pointed than that of obliqua, and the line of the 

 ventral margin is not only less curved but is somewhat constricted on the posterior 

 side. T. lata, Middendorff, 'Malac. Ross.,' found in the Arctic Seas and Behring's Straits, 

 may probably be a dwarf variety of our shell, connecting it with T. Balthica, which it 

 resembles in many of its characters. 



