140 EOCENE MOLLUSCA. 



have a greater curve, especially in the pedal region. The ribs are rounded, and about as 

 broad as the spaces between them, and the exterior appears to have been slightly pustular, 

 both over the ribs as well as between them. The valves are united, and the specimen is 

 not in good condition. (The engraved figure is shghtly enlarged.) 



3. Verticordia sulcata, /. Sowerhy. Tab. XXI, fig. 9, a, h. 



IsocARDiA SULCATA, J. Sow. Min. CoDch., tab. 295, fig. 4, 1821. 

 — — Morris. Catal. Brit. Foss., p. 204, 1854. 



Spec. Char. F. Testa minima, orbiculari vel sphceroided, tumidd, inflatd, tenui, valde 

 inaquilaterali, radiato-costulatd, costulis convexiusculis ; umhonibus magnis obliquis in- 

 curvatis ; lunuld parvd, profundd, ovatd ; marginihus crenulatis. 



Shell small, orbicular, or rather spheroidal, tumid, and inflated, thin, very inequilateral, 

 with radiating and somewhat curving ribs ; beaks large, obliquely incurved ; lunule small, 

 deep, and ovate ; margins crenulated. 



Diameter, -i^ths of an inch. 



Localities. London Clay. Potter's Bar and Sheppey {Edwards), Whetstone and Chalk 

 Farm {Wether ell). 



A few specimens only of this species have as yet been found, although they are dis- 

 tributed through several localities. These unfortunately have the two valves united, so 

 that the interior has not yet been seen. 



The shell is very tumid, and with the valves united is nearly spherical ; the riblets or 

 costulse appear to have been nearly convex ; but there is so little of the true shell or 

 exterior remaining, that I am unable positively to say what was the correct shape of these 

 ribs ; the spaces between them appear to have been about the same breadth ; the umbo 

 tumid and prominent, with the beaks much inflexed and very excentric, curving over a 

 deep luuular depression. Pyritous casts are also found at Sheppey. 



4. Verticordia propinqua, S. Wood. Tab. XXI, fig. 7. 



The specimen from v^^hich my figure is taken is merely a cast ; it comes from the 

 cabinet of Mr. Edwards, and, from its possessing a larger number of ribs or riblets and 

 being more oblique in outline than any of the other species, I have presumed it to be 

 distinct. It is from a cutting in the London Clay at Highgate. The name is, however, 

 provisional, and it is figured for the purpose of calling attention to its existence. 



The nacreous composition of these shells seems to have been unfavorable to their 

 preservation. 



