22 EOCENE MOLLUSCA. 



Ostrea flabellula. J. Sowerby. Miri. Couch., t. 253, 1819. 



— — ? Basterot. Coq. Foss. des Eav. de Bord., p. 72, 1825. 



— Deshayes. Coq. Foss. des Env. de Par., p. 366, pi. 63, figs. 5 — 7, 



1825. 



— Goldfuss. Petr. Germ., t. 11, p. 14, No. 33, pi. 76, fig. 6, a — y. 



— Galeotti. Mem. de l'Acad. de Brux., t. xii, pi. iv, fig. 6,a, b, 1837- 

 Nyst. Coq. Foss. Belg., p. 323, pi. 29, fig. 3, a, a', b, V, 1843. 



— Broun. Leth. Geogn., B. iii, p. 352, t. 39, fig. 15, a— c, 1848. 



— — /. Sowerby, in Dixon's Geol. of Sussex, p. 95, pi. 4, fig. 5, 1850. 



— — Deshayes. An. sans Vert, du Bassin de Par., p. 120, 1860. 



— deformis. Id. Coq. Foss. des Env. de Par., t. i, p. 346, pi. 55, figs 7, 8. 



— subplicata. Id. .... p. 345, pi. 48, fig. 3. 



— bifrons. Id. 2d edit. Lam., t. vii, p. 242, 1836. 



Spec. Char. 0. testa cuneatd vel ovato-orbicidari ; oalvd inferiore plicata, plicis 

 radiantibus, rugosis, arcuatis, hinc inde furcatis ; valvd superior 'e plana concent) ice striata ; 

 intiis laevi vel obsolete ad marginem denticulatd. 



Shell wedge-shaped or ovately orbicular ; lower valve plicated or ribbed ; ribs rugose, 

 radiating, and bifurcating in the older shell ; upper valve flat, concentrically striated, with 

 the inner margin finely or obsoletely denticulated. 



Longest diameter, \\ inch. 



Localities. Barton, Bracklesham, Bramshaw, Clarendon, Southampton, Stubbington, 

 Whitecliffe Bay {Edwards), Bagshot, Clewett's Green, Headley on the Hill, Orpington, 

 Sundridge, (Preshoich) . 



France, Grignon, Parnes, Courtagnon {Desk.), Bayonne {D'Archiac). 

 Belg., Le sables d'Uccle, de St. Gilles, de Foret, de Lacken, &c. {Ngst). 



The two specimens from Barton, figured in Brander, Nos. 84 and 85, pi. vii, are 

 considered by some authors to belong to two distinct species, viz., 0. jlabelhda and 

 0. cymbula. 



In Mr. Edwards's cabinet is a group of these shells from Barton, adhering to each other, 

 one of which possesses the ovate form of cgmbula, while another has the cuneate or typical 

 form of Ch. plicata, Br., 85; and I cannot imagine that they were otherwise than the 

 offspring of the same parent, and I believe that the two shells figured in Brander belong 

 to the same species. Groups of these varying forms are not uncommon also at 

 Bracklesham. 



The English specimens vary much in outline, some being cuneiform or triangular, while 

 others are oval : this difference does not appear to be the result of impediment to the 

 natural growth, and it is principally by the outward form that the specific distinction has 

 been made, the angular one constituting//<2^//w/«, and the ovate one cgmbula. Sometimes 

 this species adheres broadly and firmly to some foreign body, and a large space is left 

 upon the shell denoting the place of adherence, while in other specimens there is scarcely the 



