EROM THE INFERIOR OOLITE. 517 



marked from the other, being covered with very numerous, simple, 

 parallel, regular laminae. 



Locality. There are three specimens from Pundry in the Bristol 

 Museum, and I have obtained it from that place as well as from 

 Bradford Abbas, and from the Sands of Frocester. Other specimens 

 are at Jermyn Street. 



Dimensions of both valves 1| inch long, 3| wide, and 1 inch deep. 



Though it seems to be a not uncommon shell, I have been unable to 

 identify it with any species of which I have seen a description. 

 G. laevigata is too indistinctly described by Lycett in the Annals of 

 Nat. Hist. 1850 to be recognizable. Mr. Tawney has conjecturally 

 named the species G. tortuosa ; but it seems to me very distinct 

 from the specimens of that shell which I have seen, as well as from 

 Sowerby's figure. Phillips's figure of Gastrochcena tortuosa, though 

 nearer to it, is still much shorter and more oblique. Quenstedt's 

 figure of the smaller valve of the same species (Jura, t. 48. fig. 19) 

 is rather like, but more oblique and very different in ornamenta- 

 tion. G. radians, Morr. and Lye, has a much larger umbo, and is 

 more contorted and less oblique. G. lata, Phill., Geol. Yorksh. 

 vol. i. t. 11. fig. 16, and G. Hartmanni, Miinst., Goldf. Petr. Germ, 

 t. 115. fig. 7, are much more equivalve shells. It may possibly 

 agree with G.fornicata, Lycett, ' Cotteswold Hills,' p. 121, but seems 

 to differ in wanting the sinuations in the infero-anterior border, and 

 being less oblique. 



Gervillia compressa, n. sp. Plate XVI. fig. (5. 



Shell. flatfish, very oblique, moderately transverse; umbo very 

 anterior, not prominent, facing and sloping forward, acute, and 

 not rising above the level of the hinge-line : front auricle small 

 and convex ; hind auricle large and very flat or even concave. 

 Hinge-line straight and nearly of the same length as the shell. The 

 margin of front auricle convex, and then, after a short sharp concavity, 

 where it meets the body, continuing in a curve, almost that of an egg, 

 nearly from its acute to its obtuse end. It then curves more sud- 

 denly, and from this point a line runs up, at first slightly concave, and 

 then convex, in rear of and defining the umbo ; the posterior edge, 

 after coinciding with this line for about one sixth of its length, 

 proceeds £or some time obliquely from it, and then becomes decidedly 

 concave as it turns out to meet the posterior end of the hinge-line. 

 Surface smooth, with a few indistinct growth-striae : in front of the 

 above-mentioned line, it suddenly rises, and then becomes flatly 

 convex, being spathulate in its infero-posterior part. It slightly 

 overlaps the general margin at the antero -inferior corner. 



There is a single left valve from Nailsworth in the Jermyn-Street 

 Museum, which measures 18 lines long, 28 wide, and 10 deep. 



The most marked features are its obliquity, the sharp line behind 

 the umbo, and its very slight convexity ; thus it approaches Pteroperna 

 plana, Morr. and Lye, though it is very different from that species. 



It is rather similar to Avicula modiolaris, Goldf. Petr. Germ, 

 t. 118. fig. 5, but is a much flatter and more oblique shell. 



