114 EOCENE MOLLUSCA. 



and ventral margins curved ; lunule elongate, distinct, and rather depressed ; anal region 

 heartshaped ; teeth small near the beak ; margins smooth. 



Length, \ an inch ; height, ^ths of an inch. 



Localities. Highcliff, Barton, Brockenhurst, Hordwell {Edwards). 



Although a thin and delicate shell, it has been obtained by Mr. Edwards in great 

 abundance. The exterior is smooth and glossy, with a few concentric ridges or obtuse 

 lines of growth. The interior has a strong nacreous lustre, with an enamelled exterior. 

 The hinge-line is narrow ; it has about a dozen denticles on the pedal side, with scarcely 

 half that number on the other, and the support for cartilage is simple, somewhat elongated, 

 projecting inwardly at an angle of 45° to the dorsal margin. There is a deep depression 

 (lunule?) on the pedal region, producing a sharp elevation to the dorsal margin, with a 

 faint depression on the si phonal or anal region, but not very well defined. The extremity 

 of the siphoni-lateral margin is rather short and generally more or less pointed or subro- 

 strated ; this gives a considerable convexity to the ventral margin in the normal form. The 

 shell is thin, and the oral muscle scarcely visible, but the anal one is large and well 

 impressed. 



There are, I think, three varieties of this species ; at least, there are three different 

 forms, which I have referred to the above name, presenting as they do considerable 

 difference in outline, but not, I think, sufficient to entitle them to different specific 

 positions. Tab. XX, fig. 1, a, b, c. 



11. Nuctjla minor, Deshayes. Tab. XVIII, fig. 10. 



Nucula. mtnoe. Desk. An. sans Vert, du Bass, de Par., t. i, p. 823, pi. 64, figs. 17—20, 1860. 



Spec. Char. JV. " testa minima, ovato-trigond, turgidula, valde inaquilaterali ; postice 

 transversim truncatd ; superne declivi ; antice attenuatd, transversim tenui-sulcatd ; sulcis 

 antice paido undulatis ; lunula nulla-, ano piano , non circumscripta ; car dine angusto , pauci 

 dentato ; dentibus angustis distantibus ; fossuld minima, brevi, angustd ; marginibus sublente 

 minutissime crenulatis." — Desh. 



Shell small, ovately trigonular, slightly tumid, siphonal region short, obliquely trun- 

 cated ; pedal region ovately rounded ; concentrically ridged or sulcated ; ridges slightly 

 irregular ; no lunule ; anal region smooth, convex in the centre ; dental margin narrow, 

 teeth few and small ; margins crenulated. 



Length, gth of an inch. 



Localities. Bracklesham {Edwards). 



France. Le Guepelle, Chery-Chartreuve, Ver, Beauval, Houdan {Deshayes). 



The figure was taken from a unique and perfect specimen in the cabinet of Mr. 

 Edwards. 



So far as I am able to determine from figure and description in the work above 

 referred to, I think our little shell may be considered as identical with the Paris Basin 



