Mr. Wetherell on the Fossils of the London Clay. -163 



size. The fossil copal*, or Highgate resin, so ahuudant at 

 the Highgate Archway, occurs here but rarely. Fossil fruits 

 analogous to those of Sheppey, crabs, lobsters, sharks' teeth, 

 scales and vertebrae of fish, and the remains of a Trionyx, or 

 marine turde, have been found. If three divisions of the for- 

 mation were made, I should consider the following fossils as 

 characteristic of each division, viz. Upper, Murcx coronattis, 

 Modiola elegansy Cardium nitejis and Pcctimculus dccussaius, 

 as at the Highgate Archway. Middle, Pholadomya margari- 

 tacea, Cardium semig7~anulatum, Naidihis regalis, Nautilus 

 centralis, and Terebratida sfriattda, in the Regent's Park. 

 Lower, Axinus angulatus, Pentacrinites subbasalti/brmisf, as 

 found at Islington and in the cliffs between Heme Bay and 

 Whitstable, which are capped with diluvium resting on the 

 London clay. In enumerating the characteristic shells of 

 each division, I have principally selected those which are 

 most abundant in it, and which are either very rare, or not 

 found at all in the other divisions. For example, the Nau- 

 tilus centralis, Nautilus regalis, and Cardiu7n semigramdattim 

 are only found in the middle division. The Axinus angidatus is 

 very common in the lower, exceedingly rare in the middle, and 

 does not occur in the upper division. And lastly, th&Pectu7icidus 

 decussatus and Cardium nitcns abound in the upper, and are 

 very scarce in the middle. In making a collection of fossil 

 shells I have endeavoured to procure them at several periods 

 of growth : this is the more desirable, since it is well known 

 that many shells vary so much at different stages of growth, 

 as to appear to be of several species, when they in reality be- 

 long only to one. That there are considerable difficulties in 

 the%\'ay of accomplishing this object I admit, but the result 

 whenever it can be done, is most satisfactory. The following 

 is a classed list, including all those (railroad) shells figures 

 of which will be found in the first six volumes of Sowerby's 

 Mineral Conchology. Several of the localities are also taken 

 from the same work. Among the unfigured shells are the 

 following genera: Phasianella, Tornatella, Eulima, Cerithium, 

 Pleurotoma, Pyrula, VolutaX,^c. 



Abbreviations of the Names of Places. 

 HA. Highgate Archway. f. Finchley. hw. Well at 



• Phillips's Elementary Introduction to Mineralogy, last edition, 182.3, 

 p. .375. 



t Miller's Natural History of Crinoidea, p. 140. 



X Note by Mr. J. De Carle Sowerby.— One species of Voliita naerly re- 

 sembles Voluta Lamljcrti, differing from it however in having a longer 

 spire and in being more oval. I propose to name it Vuluta ]Vctlwrellii, as 

 a just tribute to the author of this paj)er. 



