BIVALVIA. 67 



Dogger, the Gray Limestone, the Cornbrash, the Kclloway Rock, and the Coral Rng ; 

 numerous specimens are also in the Tessonian collection from Normandy, now in the 

 British Museum. Some of these examples are almost destitute of the posterior angle, and 

 approach so nearly in the general figure to Sowerhja crassa, D'Orb. = Tsodonta Des- 

 hai/nca, Buv., that they might fiurly have been assigned to that species, if we had not the 

 assurance of M. Buvignier that his specimens from two localities are in a good state of 

 preservation, and that they are destitute of ornamentation — a feature wliich is always dis- 

 coverable in good examples of S. triangularis, whether British or Foreign. 



Mr. Wliiteaves has figured a small species of Sowerbya, ' Ann. and Mag., Nat. Hist.,' 

 August, ISGl, under the name of 8. triangularis, Phil. Having had the advantage of 

 comparing the original specimen, through the kindness of Mr. Whiteaves, with various 

 Yorkshire specimens of S. triangularis, I feel unable to coincide in the opinion that it is 

 identical with the species of Professor Phillips ; the new Oxfordshire form is much 

 smaller, less inflated, destitute of ornamentation ; and the posterior side is so short that 

 ' truncata would be an appropriate name : it is from the Coral Rag of Oxfordshire. I 

 have also found it in the Calcareous Grit at Scarborough Castle. 



The second small species figured by Mr. Whiteaves upon the same plate under the 

 name of 8. Deshagsea, Buv.? also appears to be distinct from each of the foregoing 

 examples ; the general figure is more compressed, the anterior slope is excavated, 

 which renders its lower extremity pointed ; the whole aspect somewhat resembles a 

 Nucitla. 



Our specimen figured is from the Cornbrash of Scarborough. 



Sowerbya Woodwardi, Lgc. PI. XL, figs. 27, 27 a, 27 b, 27 c. 



Testa ovato-trigona subdepressa, subaquilatera, latere posteriore breviori, planata, 

 lavigata angulo obliquo diviso, dorso et latere antico striis longitudinalibiis regularibus 

 crebris, delicate instructis. 



Shell ovately trigonal, rather depressed, subequilateral, the posterior side being the 

 shorter ; the umbones. are not very prominent nor large ; the anterior and posterior borders 

 slope obliquely downwards ; the extremities of the valves are rounded ; the surface has 

 delicate, closely arranged regular longitudinal or concentric striations, which are separated 

 from the smooth and flattened posterior side by a distinct angle. 



It is much smaller, more depressed, more lengthened, and the umbones are much less 

 elevated than in 8. triangularis. Our right hand figure is imperfect at the posterior 

 extremity, and the posterior oblique angle is not clearly shown ; the left hand figure 

 has the anterior extremity too obtusely rounded, the specimen wanting a little of its 

 border. 



Geological Position and Locality. The Great Oolite of Bussage, near to Bisley 



