FROM THE INFERIOR OOLITE. 531 



The umbones form an obtuse ridge, which is continued in a slightly- 

 spiral line to the infero-posterior point; from this ridge the 

 surface slopes flatly to each side, becoming slightly concave near 

 the margins. Surface with coarse striations formed by the growth- 

 lines and a few very delicate and distant thread-like radiations. 



This shell occurs frequently at Dundry in the state of casts, and 

 there are several specimens of it in the Bristol Museum. In the 

 Jermyn-Street Museum and my own collection there are specimens 

 from Bradford Abbas and from Half-way House with the shell 

 preserved. 



Dimensions of the closed shell: — Length 33 lines, width 17 lines, 

 depth 10 lines. 



The Dundry casts were considered by Mr. Tawney to belong to 

 the genus Myoconcha, which appears to be borne out by the shells 

 in the Jermyn-Street Museum. 



Of Sowerby's shells Modiola Hillana comes nearest in shape, but 

 has a much shorter hinge-line, which is not one half the length of 

 the shell. Modiola imbrieata, Sow. t. 212. figs. 1-3, differs in its 

 shorter hinge-line and larger anterior side, as well as in its concave 

 inferior margin. Morris and Lycett's figure of that shell is different 

 from Sowerby's. Myoconcha actceon, Morr. & Lye, is a rounder and 

 flatter form, without the protruding ear, the shelving sides, and the 

 triangular shape which so strongly define this species. 



Thracia LEGtjMrN'osA, n. sp. Plate XYIII. figs. 23, 23 a. 



Shell flatfish, very transverse, bean-shaped. Umbo minute, situ- 

 ated two thirds of the way back, and slanting, but not facing poste- 

 riorly. No lunule or escutcheon. Edges meeting all round at a 

 similar and very acute angle. Dorsal and ventral margins nearly 

 parallel, the latter being slightly concave. The side margins convex, 

 the anterior being considerably the larger. The antero-dorsal 

 region slightly flattened from an indistinct angle. The shell-sub- 

 stance very smooth, thin, and shining. 



Dimensions of the closed shell : — 3 lines long, 5 wide, and 1| deep. 



Locality. Dundry.- Two specimens are in the Bristol Museum. 



The nearest approach in general shape to this fossil is Quenstedtia 

 laevigata of Morris & Lycett, Gt. Oolite Moll. pt. 2, t. 14. figs. 13 ; 

 but in this the posterior side is smaller and the umbo larger. 

 Myacites jejunus, Quenst., Jura, t. 68. fig. 6, also bears much resem- 

 blance to it ; but in that shell the inferior side is convex and the 

 umbo less elevated. In shape it is similar to, but more angular than, 

 Cyclasfaba, Miinst., Goldf. t. 147. fig. 8, from the Wealden. It is 

 evidently most closely allied to Venus Hasina, E. A. Eomer, Yerst. 

 ool. Geb. t. 14. fig. 10, but would seem to be a somewhat less equi- 

 lateral and transverse shell. 



Turacia Studeri, Ag. Plate XIX. fig. 6. 



I have obtained from Bradford Abbas a specimen which appears to 

 agree with the shell figured by Agassiz, Et. Crit. p. 267, t. 35, and 

 there are two from Bradford in the Jermyn-Street Museum. 



