FROM THE INFERIOR OOLITE. 493 



been attached to a long Polyzoon, Encrinite, or some such object. The 

 general shape is that of a slightly squared and oblique pear, the 

 anterior edge being squarely convex, the posterior straight, the in- 

 ferior straight, but curving suddenly to meet the lateral parts. The 

 back is flat, and the three sides are so steep as to be nearly perpen- 

 dicular to the marginal plane. The surface has one or two irregular 

 and indistinct growth-swellings, but is otherwise smooth, except 

 for a few accidental bulges. 



There are several specimens of this shell in the Sharp Collection 

 in the British Museum, from the " Barnack Bag." 



Mr. Sharp's fossils have been labelled " Ostrea sulcifera, Ph. = 

 Ostrea Jlabelloides,jun." It does not seem at all similar to either 

 of these species. It shows no sign of radiation, is of quite a 

 different size and shape, and has always very steep deep sides, 

 whereas the sides of 0. Marshii, Sow. = 0. flabelloides, Lam., are 

 essentially flat. In Brown's 'Fossil Conchology' a similar shell 

 is figured and described as 0. sulcifera. Gryphcea mima, Phill. 

 Geol. Yorksh. vol. i. t. 4. fig. 6, is a very much more transverse and 

 undefined shell. 



The largest specimen measures 7 lines in length by 4 in breadth 

 and 2 in depth. The others are decidedly smaller ; some are com- 

 paratively wider, but in these instances they seem to be deformed. 



Ostrea sph^roidaiis, n. sp. Plate XV. figs. 5, 6. 



Left valve large, hemispherical, smooth. Umbo small, central, 

 prominent, and compressed. Hinge-margin wide, nearly straight. 

 Ligamental groove large, much wider than long. Shell thin, very 

 convex, but flattened on each side of the umbo, so as to form two 

 indistinct wings. Surface with laminar growth-bulges. Muscle- 

 mark rather small, circular, and subcentral. Bight valve flat. 



Size. 2^ inches in length and width, and 1 inch in depth. 



This handsome and well-characterized oyster is common in the 

 shelly bed at the base of the Inferior Oolite near Yeovil Junction. 



Gryphvea abrttpta, n.- sp. Plate XY. figs. 7, 7 a. 



Shell very convex, triangular, inequivalved. Left valve divided 

 into two portions by a small deep groove starting from the surface 

 of attachment, and running obliquely down the shell. The part of 

 the shell anterior to this equals two thirds of the whole surface, 

 and is regularly convex ; the portion posterior to it first swells out 

 into a straight rounded ridge (starting nearly from the umbo, and 

 bordering the groove), along which is the greatest diameter of the 

 shell, and immediately behind this the surface is so suddenly de- 

 pressed and flattened that it cuts the marginal plane almost at right 

 angles on the posterior side. The umbo is large and well developed, 

 but truncated by a small flat surface of attachment, which seems 

 always to occupy a similar position on the shell. The shell is 

 smooth and thin compared with that of G. sublobata (Desh.;, and 

 shows occasional irregular lines of growth. 



Length 2 inches, width \\ inch, depth 10 lines. 



