300 CONCLUDING OBSERVATIONS. 



p. 67), are correct, (and his opinions on the subject are entitled to con- 

 siderable deference), the hypothesis is untenable, since he believes that 

 the shells in question possess neither the form nor structure of fresh 

 water shells, but bear a close resemblance to a species of marine Turbo, 

 allied to T. littoreus. 



4. The Green sand (p. 69), with its beds and concretions of cherty 

 sandstone, exhibits considerable variety, both in colour, and in the nature 

 of its materials ; it is, however, clearly identified with the Chlorite sand of 

 Wiltshire by its organic remains, consisting of more than twenty kinds of 

 fossil shells, most of which also occur in the same deposit in Devonshire 

 and Wiltshire (p. 78). In some instances, the sandstone is strongly 

 impregnated with bitumen (p. 76) ; in others, it contains fragments of 

 petrified wood (p. 76) *. 



5. The Blue chalk marl or Gait (p. 80), is a remarkable division of 

 the chalk formation ; and although not always present, yet wherever it 

 does occur, maintains a striking uniformity, both in its mineralogical 

 characters, and organic remains. It contains two or three species of 

 Turbinolia ; more than thirty kinds of testacete, which in most instances 

 retain their shelly coverings in a beautiful state of preservation ; five 

 species of Crustacea ; and the scales, teeth, and vertebra of fishes. Many 

 of these fossils are peculiar to this deposit ; namely, Turbinolia Konigii, 

 Cirrus plicatus, Rostellaria carinata, Nautilus inequalis, Ammonites 

 splendens, Hamites attenuatus, 'N ucvXa pectinata, Inoceramus concentricus, 

 I. sulcatus, &c. and the Crustacea. 



The " MaUn Eock" of western Sussex (p. 84), is evidently a con- 

 tinuation of the same bed, but somewhat altered in its characters by the 

 influence of local causes. 



6. The Grey chalk marl (p. 99), is co-extensive with the chalk, 

 appearing throughout the county, on the inner edge of the escarpment 

 of the Downs. Its organic remains are very numerous : those discovered 



* I have lately obtained several examples of fossil wood, from the Blue marl of Folkstone ; 

 and these so closely resemble the specimens found at Willingdon (described at page 76), that it 

 is not improbable the latter may also belong to the lower beds of that formation. 



