24 MOLLUSCA FROM THE GREAT OOLITE. 



arched, with the umbo large and incurved ; right valve oblique and concave, its umbo 

 depressed ; hinge margin elongated, nearly horizontal, with prominent auricles ; the surface 

 of the convex valve has a few obscure radiating lines decussated by others, which are 

 concentric, irregular, and very densely arranged. 



The general aspect has a considerable resemblance to Gervillia Hartmanni (Goldfuss), 

 but it is more contorted than that shell; the valves are shorter, the diameter through them 

 is greater, and the hinge line is so much less oblique as to be nearly at right angles to 

 the axis ; owing to this figure and the length of the hinge line, the posterior auricle 

 projects considerably. 



Locality. Morcot, Rutlandshire. 



INOCERAMUS. Park. 1811. 

 INOCEHAMUS, CATILLUS, MYTILOIDES, Brong. 



Gen. Char. Shell inequivalve, sub-equilateral, ovately trigonal, umbones prominent, 

 incurved; hinge straight, nearly horizontal, consisting of a series of transverse parallel 

 teeth in each valve ; substance of the test fibre-lamellar. 



INOCERAMUS? OBLIQUUS. Tab. VI, fig. 12. 



Testa ovato-obliqud subdepressd, subaquivalvi, umbonibus prominulis subcequalibus, 

 margine cardinali brevi obliquo, margine anteriore et inferiore curvato, posteriore 

 subsinuato ; lateribus plicis concentricis elatis, angustis incequalibus ct irregularibuz, 

 interdum sub-acutis. 



Shell ovate, oblique, rather depressed, subaaquivalve, umbones prominent, nearly 

 equal, hinge margin short, oblique, anterior and inferior margins gracefully rounded, 

 posterior border slightly sinuated ; the sides of the valves concentrically plicated ; the 

 plications are elevated and narrow, irregular and unequal, sometimes acute ; the substance 

 of the shell is thin. It is more oblique, wider, and less pointed than the I. cinctm from 

 the Oolite of Ireland, and more depressed than any other Oolitic species with which 

 we have compared it; the valves are thin, frequently in opposition, and are more or 

 less compressed and distorted ; the surface is smooth, shining, and is destitute of any 

 striations. 



Length, 2| inches; breadth, 2j inches; diameter through both the valves about 

 1 inch. 



Locality. Morcot, Rutlandshire. 



INOCERAMUS FITTONI. Tab. IV, fig. 14. 



? INOCERAMUS AMYDALOIDES, Goldf. Pet., t. 115, f. 4. 



Testa tenui ovato-acutd depressd : margine cardinali obliquo posteriore subrecto ; umbo- 

 nibus subacutis, rugis concentricis in&qualibus et irregularibus. 



