318 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 2/, 



CoRBULA? Macneillii, Moriis. 



Pl. XXX. fig. 4. 



Cor. testa parva, ventricosa, arcseformi, laevigata ; subgequilaterali, antice rotundata, 

 brevi, postice carinata, trimcata. 



Shell small, smooth (or faintly striatedj, ventricosa, arceeform or 

 somewhat quadrangular, nearly equilateral, anteriorly rounded, pos- 

 terior side carinated, the carina extending from the umbo to the late- 

 ral margins, which are truncated and slightly produced. 



This shell strongly resembles the Corbula duhia, Sow., and espe- 

 cially the Corb. cucullceceformis, Dmiker (Beitrage, p. 31. t. 2. f. 6), 

 with which it so generally agrees that I should have considered it the 

 same, were it not that the incurvation of the beak (represented in 

 the figure) is somewhat different, and also that the shell is described 

 as striated. 



Compare also Corbula borealis, D'Orb. (Sir R. I. Murchison's 

 Russia, t. 41. f. 5-7). 



The hinge not having been seen, this shell is placed in Corbula 

 with some doubt, as it more nearly resembles some forms of Isocardia 

 and Cijpricardia. 



Dedicated to Mr. Macneill of Trowbridge, who has materially 

 increased our knowledge of the fossils of that vicinity. 



Locality. Abundant in the Kelloway rock near Chippenham and 

 Trowbridge. 



NucuLA (Leda) Phillipsii, Morris. 



Pl. XXX. fig. 1. 



Nuc. testa transversa, subovato-trigona, laevigata, inaequilaterali, subventricosa, 

 margine cardinali angulata. 



Shell ovately trigonal, smooth, inequilateral, slightly ventricose, 

 posterior margin rather produced, but not recurved. 



The abrupt manner in which the lateral margins meet the rounded 

 anterior margin appears to be a character of this species ; it might be 

 compared with the N. nuda, Phillips, Geol. Yorksh. pl. 5. f. .5, but 

 that shell is more transverse and inequilateral. 



Locality. In the Oxford clay near Trowbridge. 



Arca subtetragona, Morris. 

 Pl. XXX. fig. 5. 



Area testa ovato-quadrata, ventricosa, inaequilaterali, sublaevigata, latere anteriori 

 brevi, posteriori carinato ; area ligamenti rhomboidali. 



Shell ovately quadrangular, ventricose, nearly smooth, or marked 

 with shallow concentric striae ; the sides with small radiating costse, 

 more prominent on the anterior part than the posterior ; posterior side 

 strongly carinated ; ligamental area shallow, lozenge-shaped, striated ; 

 umbones prominent, distant, involute. This shell somewhat resembles 



