BIVALVIA. 139 



removed. In the clayey beds of the Eocene deposits the two valves are in contact, 

 but the margins all round are so closely united that I am unable to see anything like an 

 osselet. 



1. Verticordia roRMOSA, /S. Wood. Tab. XXI, fig. 6 a, b. 



Spec. Char. V. Testa minima, suborhiculari, vel sphceroided, titmidd, inflafd, ienui, 

 inaquilaterali, costatd ; costis paucis, distantibus, intermediis, striatis ; iimbonibus 

 prominentihis ; lunula parvd, profunda ; apice acuta, valde incurvatd ; marginihus 

 crenulatis. 



Shell small, very tumid, thin, inequilateral, with a few large radiating riblets, and 

 •wide interspaces covered with striae ; beaks small, incurved, rather prominent ; lunule 

 small, deep ; margins crenulated. 



Diameter, \ of an inch. 



Locality. London Clay, Whetstone {Wether ell). 



A single specimen, unfortunately not in good condition, is in the cabinet of 

 Mr. Wetherell, and as this came from a well-digging it may be some time ere another 

 presents itself. I am glad to have the opportunity of bringing it into notice, which the 

 owner has kindly permitted me to do. Although not perfect, there is a small portion of the 

 exterior of the shell remaining, and from this I imagine it did not possess more than half 

 the number of riblets that there are upon sulcata, perhaps not more than a dozen ; these 

 are not large nor very much elevated ; they stand far apart, with a broad intervening space, 

 and in this there are about three or four intermediate smaller rays or coarse striae. It has 

 some slight resemblance to Trigonulina ornata (D'Orbigny). 



2. Verticordia obliquata, Edwards, MS. Tab, XXI, fig. 8, a, b. 



Spec. Char. V. Testa minima suborhiculari, tumidd, injlatd, tenui, fragili ; valde 

 incBquilaterali ; costatd vel striolatd, costulis circa 26, convexiusculis ; umbonibus promi- 

 nulis, incurvatis, acutis ; lunula parvd, profunda ; marginibus crenulatis. 



Shell minute, orbicular, tumid, and inflated, thin and fragile; very inequilateral; 

 riblets about 26, rounded; beaks incurved, sharp; umbonal region prominent; lunule 

 small, deep; margins crenulated. 



Diameter, fths of an inch. 



Locality. Bracklesham {Edwards). 



A single specimen of this species is all that I have seen. It appears to be distinct 

 from the London Clay shell, differing, as it does, in some particulars ; it is rather less in 

 size, but this might be from difference in age. The ribs are not so numerous, and they 



