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SUPPLEMENT TO THE BRITISH 



Trouvelle (Calvados), Prance, and he was able to isolate one of the specimens so as to 

 show the smaller valve, which was unknown to us in England. In order to complete onr 

 description of this species, I have reproduced Mr. E. Deslongchamps figures, and it will 

 be as well to add his description. " Coquille subcirculaire, a test tres-mince. Grande 

 valve patelliforme, a sommet pointue, acuminee, ornee d'un tres grand nombre de stries 

 rayonnantes irregulieres, dont quelques-uns sont dichotomes. Petite valve concave 

 (convexe dans la figure parce qu'on la voit par l'interieur), ornee de striees nombreuses, 

 assez regulieres, paralleles aux lignes d'accroissement. Poramen en forme de fente 

 ovulaire bordee de deux grosses levres." D. Hiimphresiana appears to be a rare fossil ; 

 but there are specimens in the School of Mines Museum from the Kimmeridge Clay of 

 Studley Wood ; others in the Woodwardian Museum, Cambridge, and some indications of 

 the species have occurred in the Kimmeridge Clay taken from a depth of 659 feet at the 

 Sub-wealden boring, Netherfield, near Battle, in Sussex. 



11. Discina reflexa, Sow. Dav. Ool. Mon., p. 10, PI. X, fig. S, and Sup., PI. X, 



figs. 1 to 6. 



Orbicula LiEVis, J. Sow. (in part). Min. Con., tab. cxxxix, fig. 4, October, 1816 



(not fig. 3). 



— reflexa, Sow. Min. Con., vol. vi, p. 4, 1826. 



As stated at p. 10 of my Oolitic and Liassic Monograph, it seems probable that 

 Sowerby's two larger figures of Orbicula rqflewa were drawn from specimens derived from 

 the Coal-measures of Coalbrook Dale, and belong to a species which subsequently received 

 from Phillips the name of Orbicula nitida. This view seems confirmed, not only on 

 account of the shape and size of the specimens illustrated, but also by Sowerby's own 

 statement that " a number of these curious shells were found in one or two broken clay- 

 ironstone nodules," and I possess specimens from the clay-ironstone nodules of Coal- 

 brook Dale which entirely agree with Sowerby's figures. Sowerby refers also to his 

 species (and it is, no doubt, the one he had in view), a Discina from the Alum-clay near 

 Whitby, as well as a similar Upper-liassic shell very often found attached to Leda {Nucula) 

 ovum. We must, therefore, consider these last-named specimens from the Lias and 

 Inferior Oolite Sands of Yorkshire to represent Sowerby's species, not including his 

 doubtful figures, to which he assigns no precise formation or locality. 



One of Sowerby's illustrations of Orbicula lavis (' Min. Con.,' tab. 1 39, fig. 4) from 

 the Lias is clearly a small immature example of the species under description. The 

 other figure of the so-termed 0. Icevis (fig. 3 of ' Min. Con.') is stated to have been 

 obtained from the clay (Gault) at Folkestone. Both these specimens are in the British 

 Museum, and I doubt much whether the last named can be even considered a 



