Masterpieces of Science 



bryology will often reveal to us the structure, in 

 some degree obscured, of the prototypes of each 

 great class. 



When we can feel assured that all the indi- 

 viduals of the same species, and all the closely 

 allied species of most genera, have, within a not 

 very remote period descended from one parent, 

 and have migrated from some one birth-place; 

 and when we better know the many means of 

 migration, then, by the light which geology now 

 throws, and will continue to throw, on former 

 changes of climate and of the level of the land, 

 we shall surely be enabled to trace in an admir- 

 able manner the former migrations of the inhab- 

 itants of the whole world. Even at present, by 

 comparing the differences between the inhab- 

 itants of the sea on the opposite sides of a con- 

 tinent, and the nature of the various inhabitants 

 on that continent in relation to their apparent 

 means of immigration, some light can be thrown 

 on ancient geography. 



The noble science of geology loses glory from 

 the extreme imperfection of the record. The 

 crust of the earth, with its imbedded remains, 

 must not be looked at as a well-rilled museum, 

 but as a poor collection made at hazard and at 

 rare intervals. The accumulation of each great 

 fossiliferous formation will be recognized as hav- 

 ing depended on an unusual occurrence of favour- 

 able circumstances, and the blank intervals be- 

 tween the successive stages as having been of 

 vast duration. But we shall be able to gauge 

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