$. III. DIST. CHAR. Prototype. 75 



45. Half-shaped (scmiforme)^ retaining only 

 one side, or half, of the external form and bulk 

 of the original. 



46. Complete,, or full (expletum) retaining the 

 full bulk of the original neither complanate 

 nor half -shaped. 



c. Conditional,, 



or accidental forms arising either from the de- 

 ficiency of some part of the original, or from the 

 peculiar state in which it existed,, at the time 

 of its mineral change (v. p. 73.) can only be 

 described by the same terms, as are employed 

 to discriminate the circumstances in the re- 

 cent subject, on which these forms depend. 



Prototype. (Protypus.) 



The prototype of an extraneous fossil is the ani- 

 mal or vegetable body ( specifically considered) repre- 

 sented by that fossil. 



of the laminae of the inclosing stone ; the same species approaching 

 nearer to its genuine bulk or thickness, as the distances between, 

 the separations of the laminae increase. 



The complanntion of organized bodies, after becoming subjects 

 of the fossil kingdom, is a phenomenon by no means well account- 

 ed for. It appears, however, to depend, in some measure, on the 

 softening of the animal or vegetable substance by long maceration 

 in moisture, and the compressure of the inclosing stony matter, 

 gradually indurating by contraction. 



f Petrifactions, particularly of vegetables, frequently retain 



