42 STRATA OF TILGATE FOREST. 



endeavour to obtain some idea of the form, and structure, of the ori- 

 ginals. 



Organic Remains of the Strata of Tilgate Forest*. 

 Vegetable remains. — These occur either in the form of carbona- 

 ceous impressions in the hmestone slate and carstone ; or consist of sand- 

 stone casts of a ferruginous colour, bearing the form and external characters 

 of the original. 



1. Wood. In the state of carbon or charcoal, stiU retaining its Hgneous 

 structure. The fissures in its substance are filled, in some specimens, 

 with white calcareous spar, and in others, with pyrites of a briUiant ap- 

 pearance ; the latter quickly undergo decomposition by exposure to the air. 



It occurs in small portions, which are generally imbedded in the more 

 compact masses of carstone. 



2. The stems or culms of vegetables allied to the euphorbiae, or to 

 some species of arborescent fern ; perhaps Dicksonia ? 



The surface of these fossils is rough, being covered with oblong irre- 

 gular tubercles, disposed in longitudinal undulating lines. The trunk is 

 nearly cyhndrical, but somewhat compressed, and is contracted at irre- 

 gular intervals ; in some specimens exhibiting rudiments of branches. The 

 largest are nearly fourteen inches in circumference, and upwards of four 

 feet in length f; and from the imperfect state in which these occur, it is 

 evident that the originals attained a very large size : sections show no 

 traces of the internal structure. They are associated with impressions of 

 leaves and other vegetal remains, but my distance from the quarry has 

 prevented me from ascertaining the relation they bear to each other. 



* When the idea of this work first suggested itself, my information concerning these de- 

 posits was too imperfect for pubUcation, and their description was in consequence exchided 

 from the original plan. The organic remains I then possessed were but few and uninteresting, 

 and the plates were devoted to other objects before more illustrative specimens occurred. 

 Should circumstances permit, I shall hereafter lay before the public, delineations of several 

 extraordinary fossils recently discovered in these strata. 



t One of the finest specimens hitherto discovered is deposited in the British Museum. 



