. III. DIST. CHAR. Form. 71 



a, 34. THE EXTERNAL ESSENT.F. (Forma essent. 

 externa] exhibits the figure of the original. 



b. 35. THE INTERNAL ESSENT. F. (Forma es- 

 sent. intern a) exhibits the fabric or texture of the 

 original. 



E. 36. THE ACCIDENTAL FORM (Forma 

 Jortuita) is the configuration imparted to the reli- 

 quium either by the mineral substance, with which 

 it is combined, by the mode in which the mineral 

 change has been effected, or by the peculiar state or 

 condition of the original during its change. Hence 

 the accidental form is either 1 . mineral, 2. modal, or 

 3. conditional. 



a. 37. THE MINERAL ACCIDENT. F. (Forma fort, 

 mineralis) is found in petrifactions, and includes 

 both the external appearance and the internal 

 structure, as far as either might have been possessed 



3. Impressa sunt petrificata ex animalibus mollioribus, quae se- 

 pulta et compressa intra terrain reliquerunt figuram, sed tola con- 

 sumta, ut typus tantum reinanserit pristini animalis. 



4. Transubstantiata sunt, quae tarn interiorem, quam exterio- 

 rein structural!! in lapide ostendunt ; orta ex durioribus, quae diu- 

 tius perstilerunt in terrae gremio." Museum Tess. p. 32. To 

 the above are added, in the Sy sterna Naturae {Tom. III. p. 154. 

 "' Incrustata, more Stalactitae, ab aqua calcaria, imprimis ther- 

 ma lj Linnaeus justly remarks, however, that these last are 

 scarcely to be ranked as petrifactions. 



With respect to the different modes of formation, in extraneous 

 fossil bodies, ST.S thus stated, we have to observe, that the Redin- 



can only be considered as genuine 



