272 LONDON CLAY. 



cated. It is generally of a reddish brown colour, has a glossy surface, and 

 very much resembles a detached scale of a fish, 



4. Vermicularia Bognoriensis. 



Spiral, last volution much produced, inferior side deeply umbilicate. 



The longest diameter is about 0-5 inch; the volutions are five or six 

 in number; the produced part exceeding in length the longest diameter 

 of the shell. 



The great length of the straight portion of the tube, the height of the 

 spire, and the depth of the concave or umbilicated side, appear to be the 

 distinguishing characters of this species. The wreaths are nearly round 

 and smooth. It is gregarious, and occurs very abundantly in some parts 

 of the sandstone : a block in my possession, about four inches square, con- 

 tains nearly twenty specimens lying in rehef 



5. Pyrula . (Murex pyrus of Brander.) Foss. Hant. figs. 52, 53. 



A fine cast of this species is the only example hitherto discovered. 



6. TienidMvim planum. Min. Conch. Tab. Ixxix. fig. 1. 



This species is scarcely an inch long ; it is curved, and gently tapering ; 

 the surface is smooth, and the aperture round. It occurs in small groups, 

 and is evidently gregarious. 



7. Mya intermedia. 3Iin. Conch. Tab. Ixxvi. fig. 1. 



The width of this shell is equal to twice its length, which is seldom 

 more than 1 S inch. The anterior side is expanded, and the shell pos- 

 sesses a flatness, wliich Mr. Sowerby considers as characteristic of the 

 species. The surface is smooth, except where it is marked by the lines of 

 increase. 



8. Pinna margaritacea *. (Lamarck). 



The usu.al mode in wliich this species occurs, is that of casts covered 

 with the pearly coat of the shell; very rarely, the shell itself remains. 



* This species is described by Mr. Parkinson; {Organic Remains, Vol. iii. p. 165) and is 

 figured by Burtin, (OryctograjpJiie de Bruxelles), fig. B. PI. xviii. as a Jambonneau ou Pinne 

 marine, 



Mr. RoUo found a small block of sandstone, containing the remains of eight individuals. 



