400 GEOLOGY OF THE ISLE OF PORTLAND. 



between Stone and Hartwell, where it is covered 

 by cream-coloured freshwater limestone, resem- 

 bling the Cap of Portland, in which wings of 

 Insects, and leaflets of the Wealden ferns, have 

 been discovered by the Rev. P. B. Brodle,* and 

 my friend, the Rev. J. B. Reade, Vicar of Stone. 

 In the tertiary freshwater beds at Binstead (see 

 p. 105), there is a stratum of bituminous earthy 

 loam so like the dirt-bed, that it seems probable 

 it may have had a similar origin, and be the 

 remains of a layer of vegetable mould. 



Organic remains. — The common species of 

 marine shells, already mentioned as characteristic 

 of the strata below the Purbeck, occur more or 

 less abundantly in the several localities previously 

 mentioned. In the Portland stone, one species of 

 ammonite, of a very large size, hence named 

 Ammonites aiganteus, is often met with, and good 

 specimens may be procured of the quarry men. 

 The fossil wood is to be found in most of the 

 stone quarries, and the cycadeous plants, called 



* See the highly interesting work of Mr. Brodie, entitled, "A History of 

 the Fossil Insects in the Secondary Rocks of England," 1 vol. 8vo, with 10 

 plates, published by John Van Voorst, 1815. Mr. Brodie has discovered 

 numerous remains of small insects, belonging to forty-eight families and 

 genera, in the Wealden strata of Wilts and Bucks. I have not been so 

 fortunate as to detect any vestiges of Insects in the Wealden of the Isle of 

 Wight and Sussex ; but I have two or three wings of small beetles, from 

 Kent, and of neuropterous insects from near Stone, in Buckinghamshire 



