STRATA OF TILGATE FOREST. 43 



They are principally found in the sand and sandstone, and are covered 

 with a ferrugino-carbonaceous crust, which falls off when the surrounding 

 matrix is removed. 



I am unacquainted with any vegetables, either recent or fossil, with 

 which these remains can be identified. They bear some analogy to 

 the PhitoUthus plantites verrucosus of Marten*, but differ in the super- 

 ficial markings, and are destitute of the imbricated body observable 

 in the Derbyshire fossil. They agree in their general conformation with 

 the euphorbiae of the East Indies, but at the same time, present differences 

 sufficiently remarkable to prove their want of identity. In all probability 

 they are casts formed in the cavities cf the stems of arundinaceous plants? 

 the crust with which they are invested, being the remains of the cortical 

 covering of the original. 



3. A cyhndrical imbricated body, marked with interrupted longi- 

 tudinal strise — the medullary or internal part of a vegetable, analogous 

 to the fossils last described. It is composed of sandstone, and occurs in 

 fragments of a foot or more in length, and from six to eight inches in cir- 

 cumference. 



4. A hollow cylindrical body, slightly compressed ; the cortical or epi- 

 dermal remains of a vegetable. 



This fossil is two inches and a half long, twelve inches in circumference, 

 and one inch in thickness. The external surface is divided into compart- 

 ments of a rhomboidal form, by deep cancellated sulci, and the internal is 

 marked with interrupted longitudinal striae, apparently the impressions of 

 a body which it formerly enclosed. This specimen is decidedly the re- 

 mains of the epidermal covering of a plant, and, very probably, cf the 

 same kind as the fossil, No. 3, the markings on the external surface of 

 the one, and the impressions on the interior of the other, perfectly corre- 

 sponding. In its structure it approaches to Plantites verrucosus o£W[ai'ten, 

 but its external surface more nearly resembles that of PhitoUthus plantites 

 imbricatus-f ; it is, however, essentially distinct from either. It is pro- 



* Petrificata Derbiensia ; or. Figures and Descriptions of Petrifactions, collected in Tierhy- 

 shire, by William Marten, F.L.S. Wigan, 1809. Tab. 11, 12, 13. 

 + Petrificata Derbiensia, Tab. 14, fig. 5, and Tab. 50. 



