414 Rev. W. Buckland on the Paramoudra, and 



and one foot in diameter. Through the kindness of my learned 

 friend Dr. Bruce of Belfast, a still more perfect specimen from 

 Moira has been deposited in the Ashmolean Museum at Oxford.* 



The usual forms of these bodies are modifications of those drawn, 

 more or less elongated or compressed. No two of them are to be 

 found exactly alike in all their proportions. Their length com- 

 monly varies from one to two feet, their thickness from six to 

 twelve inches. Their substance in all cases is flint. The termi- 

 nation of these siliceous bodies is distinct, and the separation of the 

 flint from its matrix of chalk always clear and decided. Their 

 outer covering has the appearance of a thin epidermis, smooth 

 externally, and whiter than the mass of flint inclosed, which is 

 usually of a dark grey colour. The whiteness of this crust is pro- 

 bably derived from an admixture of lime with the silex, as usually 

 happens in the exterior part of common chalk flints. 



In all cases these bodies seem to have had a central aperture 

 passing into and generally through their long diameter. The 

 breadth of this aperture varies in different specimens, from half an 

 inch or less to four or five inches, but is tolerably uniform in each 

 individual. It is usually largest in the elongated varieties ; small, 

 and sometimes almost extinct in those of a more compressed form. 

 These cavities are always filled with chalk, of the same nature with 

 the matrix in which the flints are imbedded ; they appear to have 

 been filled when the chalk was in a fluid state, and could accom- 

 modate itself to all the cavities of the organic body. The upper 

 extremity of this central cavity or pipe is generally terminated 

 by folding itself outwards, so as to form a kind of lip or scroll by 

 its junction with the outer circumference, which is inflected in- 

 wards. The lower extremity of the siliceous body is usually con- 

 * Pi. 24. No. 2. 



