BIVALVIA. 95 



7. LEDA PYGM^EA, Miimter. Tab. X, fig. 11, a b. 



NUCULA PYGM^A. Munst. Apud. Goldf. Pet. Germ., vol. ii, p. 157, t. 125, fig. 17. 



S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 298, pi. 14, fig. 7, 



1840. 



Phil. En. Moll. Sic., vol. ii, p. 46, 1844. 

 Middendorff. Mem. de 1'Acad. Imp. de St. Petersb., p. 544, 1849. 



GIBBOSA. Smith. Mem. Wern. Soc., vol. viii, pi. 2, fig. 10, 1838. 

 CORBULOIDES. Id. in addendum. 



TENUIS. Phil. En. Moll. Sic., vol. i, p. 65, pi. 5, fig. 9, 1836. 



Jeffreys. Ann. Nat. Hist., vol. xix, p. 313. 

 LENTICULA. Moll. Ind. Moll. Groenl., p. 17, 1842. 



PHILIPPIANA. Nyst. Coq. Foss. de Belg., p. 224, pi. 17, fig. 5, a c, 1844. 

 LEDA PYGM/EA. Forbes. Mem. Geol. Surv., vol. i, p. 419, 1846. 



Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 230, pi. 47, fig. 10, and 



pi. P, tig. 3, 1849. 

 YOLDIA PYGM^EA. Loven. Ind. Moll. Scand., p. 35, 1846. 



Spec. Char. Testa minutd, ovato-trigonuld, subesquilatera ; tumidd, lavigatd, polifd, 

 clausd ; antice ovato-rotundatd, postice subrostratd ; lunuld indistinctd ; margine inte- 

 gerrimo. 



Shell small, triangularly ovate, subequilateral, gibbous, smooth, glossy, and closed ; 

 anterior side roundedly ovate ; posterior subrostrated, without a distinct lunule ; 

 margin very smooth. 



Longitudinal diameter, ith of an inch. 



Locality. Cor. Crag, Sutton, Ramsholt, Gedgrave. 



Clyde Beds. Recent, Mediterranean ? Britain, Scandinavia. 



This species is found in several localities of the Coralline Crag, and very abundantly 

 at Sutton. It may be further described as having a very broad hinge line furnished 

 with 8 to 12 teeth on each side of the umbo, they are angular, large, and promi- 

 nent in the centre of the area and towards the sides, with large interspaces for 

 the interlocking of the teeth of the opposite valve, by which the two valves are 

 often found in conjunction. The shell is very tumid, moderately thick and strong, 

 and perfectly closed all round, it has a somewhat prominent umbo, and is without any 

 defined lunule or corselet ; the posterior side is generally though not always the 

 larger, and its termination rather acuminated and a little curved upwards : the 

 fossette for the ligament is very small, and the muscle marks not in general deeply 

 impressed or well defined ; that by the mantle has a small sinus. The shell is glossy 

 both within and without, and slightly nacreous. My Crag specimens are small, not 

 exceeding the sixth of an inch in the transverse or greatest diameter; but a few 

 specimens from the Clyde Beds, obligingly given to me by James Smith, Esq., of 

 Jordan Hall, appear to have attained larger dimensions, and are rather less equilateral. 



This shell is given by Philippi, on the authority of Scacchi, as a species living 

 in the Mediterranean, and it is also found fossil in the Upper Tertiaries of that part 

 of the world. 



