UPPER, OR FLINTY CHALK. 159 



4. Fruit of an unknown vegetable ? 



A muciferous fruit has recently been found in the lower chalk, near 

 Lewes. It is of a flattened oval form, about two inches long, and 1 -5 

 inch wide ; the surface exhibits a ligneous structure, and the surrounding 

 chalk is tinged with a bituminous stain. 



In the malm rock of Western Sussex, a few specimens of this kind, 

 but of a small size, have been discovered near Bignor. 



These fossils closely correspond with Martin's figure of the external 

 covering of Phytolithus nuceus*, and which, notwithstanding its diminutive 

 size, that excellent writer was of opinion belonged to a species of Cocos 

 or Areca. 



Zoophytes. 



Although the remains of this class of organized beings are very 

 numerous in the chalk, they are referable but to few genera and species. 

 For the most part they bear scarcely any resemblance to known existing 

 species, and in numberless instances exhibit but shght indications of the 

 form and structure of the original. The stony corals are transmuted 

 into calcareous spar ; while the softer spongeous zoophytes are either 

 enveloped in flint or chalcedony, or form chalky ferruginous casts and 

 impressions. 



5. Madrepora centralis. Tab. xvi. figs. 2. 4. 



Stirps solitary, cyathiform, turbinated, or cylindrical ; with numerous 

 perpendicular, radiating lamellcC, alternately extending to the centre, 

 where they unite ; surface longitudinally striated: pedicle slightly ex- 

 panded. 



This species belongs to the genus Caryophillia of Lamarck; its form is 

 exceedingly various, being either turbinate, cyathiform, or cylindrical, &c. 



The specimens are usually from half an inch to two inches in length, 

 and from O'S to 0*5 inch in diameter. The external surface is marked 

 with delicate longitudinal elevations, corresponding in number with the 



* Petrificata Derbiensia, Plate xxi. fig. 6. 



