hunter's posthumous paper on fossils. 331 



m inerals, as the schorl or black tourmaline, felspar and mica, do contain 

 ' calcareous earth,' and ' apatite' contains it in combination with phos- 

 phoric acid. Hunter, with his usual caution, puts the antecedency of 

 granite to the animal creation problematically: later observations of 

 the formation of granitic minerals subsequent to fossiliferous sedimentary 

 strata, have made it conceivable, if not probable, that, in parts of the 

 earth's crust that have been subjected to such heat as has converted 

 them into ' granite,' such fossilized remains of animals as the metamor- 

 phosed strata may have contained may have been reduced to the mere 

 earthy principles of carbonates and phosphates of lime, which chemistry 

 has detected in the granitic minerals cited by Hunter. 



And now, in conclusion, to sum up the general principles which 

 Hunter recognized as having been operative in modifying and producing 

 the present condition of the surface of our planet, and in introducing 

 and preserving the evidences of organized beings therein found ; — first, 

 he exemplifies the effects of running water, as in valleys and river- 

 courses ; secondly, the deposition of the matters so transported to the 

 sea, noting the different distances to which such transported matters 

 would be spread over the sea-bottom according to their size and other 

 physical characters ; thirdly, the erosive action of the sea on coasts, as 

 moved by tides, currents, and winds ; fourthly, the power and mode of 

 operation of a retiring sea on a rising land ; fifthly, igneous expansive 

 force and volcanic eruptions ; and sixthly, deposits through animal or 

 organic agency. 



These are recognized geological dynamics, operating in the actual 

 system of things, strictly included in that class of causes, and agreeable 

 with " our mode of reasoning," as Hunter terms it, which is, viz. " by 

 supposing from the state of the earth as it is now, what must have 

 taken place formerly." 



Only in two instances, already referred to, does Hunter deviate from 

 this strictly philosophic track : it is when he brings in the old hypothesis 

 of a change in the inclination of the earth's axis to account for the 

 presence of what he believed to be remains of tropical animals in the 

 strata of cold or temperate climates ; and where he alludes to the 

 attractive power of a comet upon the mass of waters of the earth, or 

 as having the power to add to that aqueous mass. 



Other evidence, by fossil remains, of a warmer or more equable, and 

 perhaps of both a warmer and more equable, climate having prevailed 

 in the latitude of London, has been since abundantly obtained : and 

 there are not wanting Fellows of the Geological Society who still, like 

 Hunter, advocate a change in the ecliptic : but every accession to our 

 knowledge of the local circumstances that influence local climates, and 



