BIVALVIA. 127 



France: Damery, Montmirel, Conrtagnon (Desk.). 



Belgium : Les sables de Laecken, de Jette, de Foret, et de Louvain {Nyst). 

 This elegant little shell appears to be rare. The ridges on the exterior are elevated, 

 distinct, and large, with deep furrows between them ; the furrows are nearly as broad as 

 the ridges. On the siphonal region there is a distinct and elevated keel, sloping from the 

 umbo to the extremity of the siphoni-lateral margin. 



4. Leda minima, /. Sowerby. Tab. XVII, fig. 7, a — e. 



Nucula minima. J. Sow. Min. Conch., t. 192, fig. 8, 1818. 



Spec. Char. L. testa minima, ovato-lanccolatd, elongatd, tumidd, subaquilaterali, 

 eoncentrice striata striis numerosis prominentibus ; pedi-regione rotunda! a ; siphoni-regione 

 rostratd, sub -acuminata ; umbonibus minimis, approximatis) ano mat/no, lanceolato, angulo 

 mediano bipartito, angulo obtusiore conscripto ; cardine crassiusculo, multidentato ; fossuld 

 minima, profunda. 



Shell small, elongately ovate, tumid, nearly equilateral ; pedal region rounded, siphoni- 

 lateral pointed ; beaks small, approximate, covered with concentric stria? or ridges ; 

 corselet distinct, elevated in the centre ; dental margin thick, with numerous teeth ; car- 

 tilaginous support small and deep. 



Length, \ of an inch ; height, yth of an inch. 



Locality. Barton, Bracklesham, Bramshaw, Brook, Highcliff {Edwards). 



There are three or four species of this genus about the same magnitude, possessing 

 many similar characters, which have been found in the British Eocene deposits, and it is 

 somewhat difficult to say which was the one intended by Mr. Sowerby for N. minima. 

 The present one is abundant, and probably was the one his figure is designed to 

 represent. He says, " Transversely ovate, convex, transversely striated." The striae in 

 this species cover the entire surface ; they are fine and rounded, extending from the 

 pedilateral margin to the angular ridge on the slope of the siphonal region, beyond which 

 is a large corselet ; this is of a lanceolate form, divided by a central ridge, the upper 

 portion of which is finely striated. There is a row of angular teeth (at least a dozen) on 

 each side of the cartilage- pit. 



There are two varieties of this shell, one of which strongly resembles the figure of 

 L. gracilis, Desh. {' An. sans Vert, du Bas. de Par.,' p. 831, pi. 64, figs. 24 — 2C) ; and 

 several differences are presented, as might be supposed, among our numerous 

 specimens; some have the pedal region almost smooth, as if from abrasion on that part, 

 which is generally buried by the animal in the living state. 



